| Message ID | eba39e4d-fb5f-c9d3-0d51-001f8d584d51@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | i2c: i801: Series with minor improvements | expand |
Hi Heiner, On Fri, 15 Apr 2022 18:58:03 +0200, Heiner Kallweit wrote: > This patch factors out non-block pre/post processing to a new function > i801_single_transaction(), complementing existing function > i801_block_transaction(). This makes i801_access() better readable. I like the idea, but I have objections about some implementation details, see below. > Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com> > --- > drivers/i2c/busses/i2c-i801.c | 95 +++++++++++++++++++++-------------- > 1 file changed, 58 insertions(+), 37 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c > index bf77f8640..8c2245f38 100644 > --- a/drivers/i2c/busses/i2c-i801.c > +++ b/drivers/i2c/busses/i2c-i801.c > @@ -771,6 +771,62 @@ static int i801_block_transaction(struct i801_priv *priv, union i2c_smbus_data * > return result; > } > > +/* Single transaction function */ The term "single transaction" is a bit misleading. Block transactions are also single transactions, in the sense that there's one start condition at the beginning and one stop condition at the end. I'd rather call non-block transactions "single value transactions" or "simple transactions". > +static int i801_single_transaction(struct i801_priv *priv, union i2c_smbus_data *data, > + char read_write, int command) > +{ > + int xact, ret; > + > + switch (command) { > + case I2C_SMBUS_QUICK: > + xact = I801_QUICK; > + break; > + case I2C_SMBUS_BYTE: > + xact = I801_BYTE; > + break; Previous 2 lines are indented with spaces instead of tabs. > + case I2C_SMBUS_BYTE_DATA: > + if (read_write == I2C_SMBUS_WRITE) > + outb_p(data->byte, SMBHSTDAT0(priv)); > + xact = I801_BYTE_DATA; > + break; > + case I2C_SMBUS_WORD_DATA: > + if (read_write == I2C_SMBUS_WRITE) { > + outb_p(data->word & 0xff, SMBHSTDAT0(priv)); > + outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv)); > + } > + xact = I801_WORD_DATA; > + break; > + case I2C_SMBUS_PROC_CALL: > + outb_p(data->word & 0xff, SMBHSTDAT0(priv)); > + outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv)); > + xact = I801_PROC_CALL; > + break; > + default: > + return -EOPNOTSUPP; That's never going to happen. Generally speaking, I'm worried about having the same switch/case construct here that we already have in i801_access. Looks to me like we are doing half of the work here and the other half there and I fail to see the rationale for splitting the work like that. I mean, I see how it solves the asymmetry between the block and non-block code paths, but the result doesn't look appealing. From a performance perspective it's questionable too. What prevents us from doing all the work on either side? Maybe we should move more code into i801_single_transaction (possibly in a subsequent patch)? > + } > + > + ret = i801_transaction(priv, xact); > + Traditionally no blank line here. > + if (ret || read_write == I2C_SMBUS_WRITE) > + return ret; > + > + switch (command) { > + case I2C_SMBUS_BYTE: > + case I2C_SMBUS_BYTE_DATA: > + data->byte = inb_p(SMBHSTDAT0(priv)); > + break; > + case I2C_SMBUS_WORD_DATA: > + case I2C_SMBUS_PROC_CALL: > + data->word = inb_p(SMBHSTDAT0(priv)) + > + (inb_p(SMBHSTDAT1(priv)) << 8); > + break; > + default: > + break; Default case is not needed. > + } > + > + return 0; > +} > + > static void i801_set_hstadd(struct i801_priv *priv, u8 addr, char read_write) > { > addr <<= 1; > @@ -784,9 +840,7 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, > unsigned short flags, char read_write, u8 command, > int size, union i2c_smbus_data *data) > { > - int hwpec; > - int block = 0; > - int ret, xact; > + int hwpec, ret, block = 0; > struct i801_priv *priv = i2c_get_adapdata(adap); > > mutex_lock(&priv->acpi_lock); > @@ -804,36 +858,23 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, > switch (size) { > case I2C_SMBUS_QUICK: > i801_set_hstadd(priv, addr, read_write); > - xact = I801_QUICK; > break; > case I2C_SMBUS_BYTE: > i801_set_hstadd(priv, addr, read_write); > if (read_write == I2C_SMBUS_WRITE) > outb_p(command, SMBHSTCMD(priv)); > - xact = I801_BYTE; > break; > case I2C_SMBUS_BYTE_DATA: > i801_set_hstadd(priv, addr, read_write); > outb_p(command, SMBHSTCMD(priv)); > - if (read_write == I2C_SMBUS_WRITE) > - outb_p(data->byte, SMBHSTDAT0(priv)); > - xact = I801_BYTE_DATA; > break; > case I2C_SMBUS_WORD_DATA: > i801_set_hstadd(priv, addr, read_write); > outb_p(command, SMBHSTCMD(priv)); > - if (read_write == I2C_SMBUS_WRITE) { > - outb_p(data->word & 0xff, SMBHSTDAT0(priv)); > - outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv)); > - } > - xact = I801_WORD_DATA; > break; > case I2C_SMBUS_PROC_CALL: > i801_set_hstadd(priv, addr, I2C_SMBUS_WRITE); > outb_p(command, SMBHSTCMD(priv)); > - outb_p(data->word & 0xff, SMBHSTDAT0(priv)); > - outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv)); > - xact = I801_PROC_CALL; > read_write = I2C_SMBUS_READ; > break; > case I2C_SMBUS_BLOCK_DATA: > @@ -883,7 +924,7 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, > if (block) > ret = i801_block_transaction(priv, data, read_write, size); > else > - ret = i801_transaction(priv, xact); > + ret = i801_single_transaction(priv, data, read_write, size); > > /* Some BIOSes don't like it when PEC is enabled at reboot or resume > time, so we forcibly disable it after every transaction. Turn off > @@ -891,26 +932,6 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, > if (hwpec || block) > outb_p(inb_p(SMBAUXCTL(priv)) & > ~(SMBAUXCTL_CRC | SMBAUXCTL_E32B), SMBAUXCTL(priv)); > - > - if (block) > - goto out; > - if (ret) > - goto out; > - if ((read_write == I2C_SMBUS_WRITE) || (xact == I801_QUICK)) > - goto out; > - > - switch (xact) { > - case I801_BYTE: /* Result put in SMBHSTDAT0 */ > - case I801_BYTE_DATA: > - data->byte = inb_p(SMBHSTDAT0(priv)); > - break; > - case I801_WORD_DATA: > - case I801_PROC_CALL: > - data->word = inb_p(SMBHSTDAT0(priv)) + > - (inb_p(SMBHSTDAT1(priv)) << 8); > - break; > - } > - > out: > /* > * Unlock the SMBus device for use by BIOS/ACPI,
On 10.06.2022 13:03, Jean Delvare wrote: > Hi Heiner, > > On Fri, 15 Apr 2022 18:58:03 +0200, Heiner Kallweit wrote: >> This patch factors out non-block pre/post processing to a new function >> i801_single_transaction(), complementing existing function >> i801_block_transaction(). This makes i801_access() better readable. > > I like the idea, but I have objections about some implementation > details, see below. > >> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com> >> --- >> drivers/i2c/busses/i2c-i801.c | 95 +++++++++++++++++++++-------------- >> 1 file changed, 58 insertions(+), 37 deletions(-) >> >> diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c >> index bf77f8640..8c2245f38 100644 >> --- a/drivers/i2c/busses/i2c-i801.c >> +++ b/drivers/i2c/busses/i2c-i801.c >> @@ -771,6 +771,62 @@ static int i801_block_transaction(struct i801_priv *priv, union i2c_smbus_data * >> return result; >> } >> >> +/* Single transaction function */ > > The term "single transaction" is a bit misleading. Block transactions > are also single transactions, in the sense that there's one start > condition at the beginning and one stop condition at the end. I'd > rather call non-block transactions "single value transactions" or > "simple transactions". > OK >> +static int i801_single_transaction(struct i801_priv *priv, union i2c_smbus_data *data, >> + char read_write, int command) >> +{ >> + int xact, ret; >> + >> + switch (command) { >> + case I2C_SMBUS_QUICK: >> + xact = I801_QUICK; >> + break; >> + case I2C_SMBUS_BYTE: >> + xact = I801_BYTE; >> + break; > > Previous 2 lines are indented with spaces instead of tabs. > OK >> + case I2C_SMBUS_BYTE_DATA: >> + if (read_write == I2C_SMBUS_WRITE) >> + outb_p(data->byte, SMBHSTDAT0(priv)); >> + xact = I801_BYTE_DATA; >> + break; >> + case I2C_SMBUS_WORD_DATA: >> + if (read_write == I2C_SMBUS_WRITE) { >> + outb_p(data->word & 0xff, SMBHSTDAT0(priv)); >> + outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv)); >> + } >> + xact = I801_WORD_DATA; >> + break; >> + case I2C_SMBUS_PROC_CALL: >> + outb_p(data->word & 0xff, SMBHSTDAT0(priv)); >> + outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv)); >> + xact = I801_PROC_CALL; >> + break; >> + default: >> + return -EOPNOTSUPP; > > That's never going to happen. > > Generally speaking, I'm worried about having the same switch/case > construct here that we already have in i801_access. Looks to me like we > are doing half of the work here and the other half there and I fail to > see the rationale for splitting the work like that. I mean, I see how > it solves the asymmetry between the block and non-block code paths, but > the result doesn't look appealing. From a performance perspective it's > questionable too. > > What prevents us from doing all the work on either side? Maybe we > should move more code into i801_single_transaction (possibly in a > subsequent patch)? > Makes sense. Ill add this in v2. >> + } >> + >> + ret = i801_transaction(priv, xact); >> + > > Traditionally no blank line here. > OK >> + if (ret || read_write == I2C_SMBUS_WRITE) >> + return ret; >> + >> + switch (command) { >> + case I2C_SMBUS_BYTE: >> + case I2C_SMBUS_BYTE_DATA: >> + data->byte = inb_p(SMBHSTDAT0(priv)); >> + break; >> + case I2C_SMBUS_WORD_DATA: >> + case I2C_SMBUS_PROC_CALL: >> + data->word = inb_p(SMBHSTDAT0(priv)) + >> + (inb_p(SMBHSTDAT1(priv)) << 8); >> + break; >> + default: >> + break; > > Default case is not needed. > OK >> + } >> + >> + return 0; >> +} >> + >> static void i801_set_hstadd(struct i801_priv *priv, u8 addr, char read_write) >> { >> addr <<= 1; >> @@ -784,9 +840,7 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, >> unsigned short flags, char read_write, u8 command, >> int size, union i2c_smbus_data *data) >> { >> - int hwpec; >> - int block = 0; >> - int ret, xact; >> + int hwpec, ret, block = 0; >> struct i801_priv *priv = i2c_get_adapdata(adap); >> >> mutex_lock(&priv->acpi_lock); >> @@ -804,36 +858,23 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, >> switch (size) { >> case I2C_SMBUS_QUICK: >> i801_set_hstadd(priv, addr, read_write); >> - xact = I801_QUICK; >> break; >> case I2C_SMBUS_BYTE: >> i801_set_hstadd(priv, addr, read_write); >> if (read_write == I2C_SMBUS_WRITE) >> outb_p(command, SMBHSTCMD(priv)); >> - xact = I801_BYTE; >> break; >> case I2C_SMBUS_BYTE_DATA: >> i801_set_hstadd(priv, addr, read_write); >> outb_p(command, SMBHSTCMD(priv)); >> - if (read_write == I2C_SMBUS_WRITE) >> - outb_p(data->byte, SMBHSTDAT0(priv)); >> - xact = I801_BYTE_DATA; >> break; >> case I2C_SMBUS_WORD_DATA: >> i801_set_hstadd(priv, addr, read_write); >> outb_p(command, SMBHSTCMD(priv)); >> - if (read_write == I2C_SMBUS_WRITE) { >> - outb_p(data->word & 0xff, SMBHSTDAT0(priv)); >> - outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv)); >> - } >> - xact = I801_WORD_DATA; >> break; >> case I2C_SMBUS_PROC_CALL: >> i801_set_hstadd(priv, addr, I2C_SMBUS_WRITE); >> outb_p(command, SMBHSTCMD(priv)); >> - outb_p(data->word & 0xff, SMBHSTDAT0(priv)); >> - outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv)); >> - xact = I801_PROC_CALL; >> read_write = I2C_SMBUS_READ; >> break; >> case I2C_SMBUS_BLOCK_DATA: >> @@ -883,7 +924,7 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, >> if (block) >> ret = i801_block_transaction(priv, data, read_write, size); >> else >> - ret = i801_transaction(priv, xact); >> + ret = i801_single_transaction(priv, data, read_write, size); >> >> /* Some BIOSes don't like it when PEC is enabled at reboot or resume >> time, so we forcibly disable it after every transaction. Turn off >> @@ -891,26 +932,6 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, >> if (hwpec || block) >> outb_p(inb_p(SMBAUXCTL(priv)) & >> ~(SMBAUXCTL_CRC | SMBAUXCTL_E32B), SMBAUXCTL(priv)); >> - >> - if (block) >> - goto out; >> - if (ret) >> - goto out; >> - if ((read_write == I2C_SMBUS_WRITE) || (xact == I801_QUICK)) >> - goto out; >> - >> - switch (xact) { >> - case I801_BYTE: /* Result put in SMBHSTDAT0 */ >> - case I801_BYTE_DATA: >> - data->byte = inb_p(SMBHSTDAT0(priv)); >> - break; >> - case I801_WORD_DATA: >> - case I801_PROC_CALL: >> - data->word = inb_p(SMBHSTDAT0(priv)) + >> - (inb_p(SMBHSTDAT1(priv)) << 8); >> - break; >> - } >> - >> out: >> /* >> * Unlock the SMBus device for use by BIOS/ACPI, > >
diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c index bf77f8640..8c2245f38 100644 --- a/drivers/i2c/busses/i2c-i801.c +++ b/drivers/i2c/busses/i2c-i801.c @@ -771,6 +771,62 @@ static int i801_block_transaction(struct i801_priv *priv, union i2c_smbus_data * return result; } +/* Single transaction function */ +static int i801_single_transaction(struct i801_priv *priv, union i2c_smbus_data *data, + char read_write, int command) +{ + int xact, ret; + + switch (command) { + case I2C_SMBUS_QUICK: + xact = I801_QUICK; + break; + case I2C_SMBUS_BYTE: + xact = I801_BYTE; + break; + case I2C_SMBUS_BYTE_DATA: + if (read_write == I2C_SMBUS_WRITE) + outb_p(data->byte, SMBHSTDAT0(priv)); + xact = I801_BYTE_DATA; + break; + case I2C_SMBUS_WORD_DATA: + if (read_write == I2C_SMBUS_WRITE) { + outb_p(data->word & 0xff, SMBHSTDAT0(priv)); + outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv)); + } + xact = I801_WORD_DATA; + break; + case I2C_SMBUS_PROC_CALL: + outb_p(data->word & 0xff, SMBHSTDAT0(priv)); + outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv)); + xact = I801_PROC_CALL; + break; + default: + return -EOPNOTSUPP; + } + + ret = i801_transaction(priv, xact); + + if (ret || read_write == I2C_SMBUS_WRITE) + return ret; + + switch (command) { + case I2C_SMBUS_BYTE: + case I2C_SMBUS_BYTE_DATA: + data->byte = inb_p(SMBHSTDAT0(priv)); + break; + case I2C_SMBUS_WORD_DATA: + case I2C_SMBUS_PROC_CALL: + data->word = inb_p(SMBHSTDAT0(priv)) + + (inb_p(SMBHSTDAT1(priv)) << 8); + break; + default: + break; + } + + return 0; +} + static void i801_set_hstadd(struct i801_priv *priv, u8 addr, char read_write) { addr <<= 1; @@ -784,9 +840,7 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, unsigned short flags, char read_write, u8 command, int size, union i2c_smbus_data *data) { - int hwpec; - int block = 0; - int ret, xact; + int hwpec, ret, block = 0; struct i801_priv *priv = i2c_get_adapdata(adap); mutex_lock(&priv->acpi_lock); @@ -804,36 +858,23 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, switch (size) { case I2C_SMBUS_QUICK: i801_set_hstadd(priv, addr, read_write); - xact = I801_QUICK; break; case I2C_SMBUS_BYTE: i801_set_hstadd(priv, addr, read_write); if (read_write == I2C_SMBUS_WRITE) outb_p(command, SMBHSTCMD(priv)); - xact = I801_BYTE; break; case I2C_SMBUS_BYTE_DATA: i801_set_hstadd(priv, addr, read_write); outb_p(command, SMBHSTCMD(priv)); - if (read_write == I2C_SMBUS_WRITE) - outb_p(data->byte, SMBHSTDAT0(priv)); - xact = I801_BYTE_DATA; break; case I2C_SMBUS_WORD_DATA: i801_set_hstadd(priv, addr, read_write); outb_p(command, SMBHSTCMD(priv)); - if (read_write == I2C_SMBUS_WRITE) { - outb_p(data->word & 0xff, SMBHSTDAT0(priv)); - outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv)); - } - xact = I801_WORD_DATA; break; case I2C_SMBUS_PROC_CALL: i801_set_hstadd(priv, addr, I2C_SMBUS_WRITE); outb_p(command, SMBHSTCMD(priv)); - outb_p(data->word & 0xff, SMBHSTDAT0(priv)); - outb_p((data->word & 0xff00) >> 8, SMBHSTDAT1(priv)); - xact = I801_PROC_CALL; read_write = I2C_SMBUS_READ; break; case I2C_SMBUS_BLOCK_DATA: @@ -883,7 +924,7 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, if (block) ret = i801_block_transaction(priv, data, read_write, size); else - ret = i801_transaction(priv, xact); + ret = i801_single_transaction(priv, data, read_write, size); /* Some BIOSes don't like it when PEC is enabled at reboot or resume time, so we forcibly disable it after every transaction. Turn off @@ -891,26 +932,6 @@ static s32 i801_access(struct i2c_adapter *adap, u16 addr, if (hwpec || block) outb_p(inb_p(SMBAUXCTL(priv)) & ~(SMBAUXCTL_CRC | SMBAUXCTL_E32B), SMBAUXCTL(priv)); - - if (block) - goto out; - if (ret) - goto out; - if ((read_write == I2C_SMBUS_WRITE) || (xact == I801_QUICK)) - goto out; - - switch (xact) { - case I801_BYTE: /* Result put in SMBHSTDAT0 */ - case I801_BYTE_DATA: - data->byte = inb_p(SMBHSTDAT0(priv)); - break; - case I801_WORD_DATA: - case I801_PROC_CALL: - data->word = inb_p(SMBHSTDAT0(priv)) + - (inb_p(SMBHSTDAT1(priv)) << 8); - break; - } - out: /* * Unlock the SMBus device for use by BIOS/ACPI,
This patch factors out non-block pre/post processing to a new function i801_single_transaction(), complementing existing function i801_block_transaction(). This makes i801_access() better readable. Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com> --- drivers/i2c/busses/i2c-i801.c | 95 +++++++++++++++++++++-------------- 1 file changed, 58 insertions(+), 37 deletions(-)