| Message ID | 20210521201913.2gapcmrzynxekro7@runtux.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [1/1] spi-sun6i: Fix chipselect/clock bug | expand |
On Fri, 21 May 2021 22:19:13 +0200 Ralf Schlatterbeck <rsc@runtux.com> wrote: Hi, > From: Mirko Vogt <mirko-dev|linux@nanl.de> > > The current sun6i SPI implementation initializes the transfer too early, > resulting in SCK going high before the transfer. When using an additional > (gpio) chipselect with sun6i, the chipselect is asserted at a time when > clock is high, making the SPI transfer fail. > > This is due to SUN6I_GBL_CTL_BUS_ENABLE being written into > SUN6I_GBL_CTL_REG at an early stage. Moving that to the transfer > function, hence, right before the transfer starts, mitigates that > problem. > > Signed-off-by: Mirko Vogt <mirko-dev|linux@nanl.de> > Signed-off-by: Ralf Schlatterbeck <rsc@runtux.com> Looks good to me now, thanks for the changes! Reviewed-by: Andre Przywara <andre.przywara@arm.com> Some comments for future contributions (should not hold back that patch, I think): - Single patch set series don't bother to have a "1/1" after the "PATCH". - You are expected to increase the version number when you send a new version, to show that *this* is better than the previous post and this version should be merged. Otherwise the maintainer might pick the wrong version. "git format-patch -v2" and "git send-email" will automatically take care of this. > --- > Updated patch with suggested improvements by Andre Przywara > For oscilloscope screenshots with/without the patch, see my blog post > https://blog.runtux.com/posts/2019/04/18/ > or the discussion in the armbian forum at > https://forum.armbian.com/topic/4330-spi-gpio-chip-select-support/ > (my logo there is a penguin). Please keep in mind that text after the dashes doesn't make it in it repo, so this information would be lost there. Also, in general links in commit messages are somewhat frowned upon, since they tend to 404 sooner or later. So ideally you can put a condensed version of your findings into the commit message? Don't worry if it grows long, it is not uncommon to have a 2 page commit message for a one-liner patch. Cheers, Andre > > drivers/spi/spi-sun6i.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/drivers/spi/spi-sun6i.c b/drivers/spi/spi-sun6i.c > index cc8401980125..23ad052528db 100644 > --- a/drivers/spi/spi-sun6i.c > +++ b/drivers/spi/spi-sun6i.c > @@ -379,6 +379,10 @@ static int sun6i_spi_transfer_one(struct spi_master *master, > } > > sun6i_spi_write(sspi, SUN6I_CLK_CTL_REG, reg); > + /* Finally enable the bus - doing so before might raise SCK to HIGH */ > + reg = sun6i_spi_read(sspi, SUN6I_GBL_CTL_REG); > + reg |= SUN6I_GBL_CTL_BUS_ENABLE; > + sun6i_spi_write(sspi, SUN6I_GBL_CTL_REG, reg); > > /* Setup the transfer now... */ > if (sspi->tx_buf) > @@ -504,7 +508,7 @@ static int sun6i_spi_runtime_resume(struct device *dev) > } > > sun6i_spi_write(sspi, SUN6I_GBL_CTL_REG, > - SUN6I_GBL_CTL_BUS_ENABLE | SUN6I_GBL_CTL_MASTER | SUN6I_GBL_CTL_TP); > + SUN6I_GBL_CTL_MASTER | SUN6I_GBL_CTL_TP); > > return 0; >
On Mon, May 24, 2021 at 01:33:01PM +0100, Andre Przywara wrote: > - Single patch set series don't bother to have a "1/1" after the > "PATCH". > - You are expected to increase the version number when you send a new > version, to show that *this* is better than the previous post and > this version should be merged. Otherwise the maintainer might pick > the wrong version. "git format-patch -v2" and "git send-email" will > automatically take care of this. OK I'll keep that in mind. > Please keep in mind that text after the dashes doesn't make it in it > repo, so this information would be lost there. Also, in general links in > commit messages are somewhat frowned upon, since they tend to 404 > sooner or later. So ideally you can put a condensed version of your > findings into the commit message? Don't worry if it grows long, it is > not uncommon to have a 2 page commit message for a one-liner patch. This was intentional, the commit message is only the upper part. The Links were meant to give a lot of details why the patch fixes something. I think the commit message already explains the condensed findings. I've put this additional explanation text after the '---' to not need an additional Patch 0/1 email ;-) Thanks! Ralf -- Dr. Ralf Schlatterbeck Tel: +43/2243/26465-16 Open Source Consulting www: www.runtux.com Reichergasse 131, A-3411 Weidling email: office@runtux.com
On Fri, May 21, 2021 at 10:19:13PM +0200, Ralf Schlatterbeck wrote: > From: Mirko Vogt <mirko-dev|linux@nanl.de> > > The current sun6i SPI implementation initializes the transfer too early, > resulting in SCK going high before the transfer. When using an additional > (gpio) chipselect with sun6i, the chipselect is asserted at a time when > clock is high, making the SPI transfer fail. Please don't send new patches in reply to old threads, this makes it hard to follow what is going on and creates confusion as to what the current version of things is and means things can easily get missed if the earlier thread gets discarded - this goes along with the thing Andre mentioned about flagging the version of the patch in the subject line.
On Tue, May 25, 2021 at 03:35:51PM +0100, Mark Brown wrote: > On Fri, May 21, 2021 at 10:19:13PM +0200, Ralf Schlatterbeck wrote: > > From: Mirko Vogt <mirko-dev|linux@nanl.de> > > > > The current sun6i SPI implementation initializes the transfer too early, > > resulting in SCK going high before the transfer. When using an additional > > (gpio) chipselect with sun6i, the chipselect is asserted at a time when > > clock is high, making the SPI transfer fail. > > Please don't send new patches in reply to old threads, this makes > it hard to follow what is going on and creates confusion as to > what the current version of things is and means things can easily > get missed if the earlier thread gets discarded - this goes along > with the thing Andre mentioned about flagging the version of the > patch in the subject line. OK, let me know if I should repost in new thread with increased version number in the subject. Thanks, Ralf -- Dr. Ralf Schlatterbeck Tel: +43/2243/26465-16 Open Source Consulting www: www.runtux.com Reichergasse 131, A-3411 Weidling email: office@runtux.com
On 5/27/21 1:39 PM, Ralf Schlatterbeck wrote > OK, let me know if I should repost in new thread with increased version > number in the subjec Assuming this wasn't answered yet: was this just a comment for further patches and things are going their way or should it indeed be resent as new thread/version with respective changes applied? Can I do something to help / resolve this? Have a nice weekend mirko
I've reposted as v2 in a new thread. -- Ralf Schlatterbeck
diff --git a/drivers/spi/spi-sun6i.c b/drivers/spi/spi-sun6i.c index cc8401980125..23ad052528db 100644 --- a/drivers/spi/spi-sun6i.c +++ b/drivers/spi/spi-sun6i.c @@ -379,6 +379,10 @@ static int sun6i_spi_transfer_one(struct spi_master *master, } sun6i_spi_write(sspi, SUN6I_CLK_CTL_REG, reg); + /* Finally enable the bus - doing so before might raise SCK to HIGH */ + reg = sun6i_spi_read(sspi, SUN6I_GBL_CTL_REG); + reg |= SUN6I_GBL_CTL_BUS_ENABLE; + sun6i_spi_write(sspi, SUN6I_GBL_CTL_REG, reg); /* Setup the transfer now... */ if (sspi->tx_buf) @@ -504,7 +508,7 @@ static int sun6i_spi_runtime_resume(struct device *dev) } sun6i_spi_write(sspi, SUN6I_GBL_CTL_REG, - SUN6I_GBL_CTL_BUS_ENABLE | SUN6I_GBL_CTL_MASTER | SUN6I_GBL_CTL_TP); + SUN6I_GBL_CTL_MASTER | SUN6I_GBL_CTL_TP); return 0;