| Message ID | 20220803065737.14752-1-sherry.sun@nxp.com |
|---|---|
| State | New |
| Headers | show |
| Series | tty: serial: imx: initialize peripheral_config/peripheral_size for sdma config | expand |
Hello Sherry, On 03.08.22 08:57, Sherry Sun wrote: > Since commit 824a0a02cd74 ("dmaengine: imx-sdma: Add multi fifo support") > adds the use of dma_slave_config->peripheral_config/peripheral_size to > sdma driver, the client drivers like uart need to initialize the > peripheral_config/peripheral_size for sdma, otherwise, the random value > of local variable slave_config may cause unexpected peripheral_config > and make sdma mess up. > If this a fix, please add a Fixes: tag. I am not sure it is though, see below. > Signed-off-by: Sherry Sun <sherry.sun@nxp.com> > --- > drivers/tty/serial/imx.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c > index 522445a8f666..bb8c2a712e94 100644 > --- a/drivers/tty/serial/imx.c > +++ b/drivers/tty/serial/imx.c > @@ -1320,6 +1320,8 @@ static int imx_uart_dma_init(struct imx_port *sport) This function starts with struct dma_slave_config slave_config = {}; > slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; > /* one byte less than the watermark level to enable the aging timer */ > slave_config.src_maxburst = RXTL_DMA - 1; > + slave_config.peripheral_config = NULL; > + slave_config.peripheral_size = 0; So these are already zero-initialized. > ret = dmaengine_slave_config(sport->dma_chan_rx, &slave_config); > if (ret) { > dev_err(dev, "error in RX dma configuration.\n"); > @@ -1346,6 +1348,8 @@ static int imx_uart_dma_init(struct imx_port *sport) > slave_config.dst_addr = sport->port.mapbase + URTX0; > slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; > slave_config.dst_maxburst = TXTL_DMA; > + slave_config.peripheral_config = NULL; > + slave_config.peripheral_size = 0; Not sure if this is required. If preceding dmaengine_slave_config() indeed makes clearing necessary, you should note that in the commit message. Cheers, Ahmad > ret = dmaengine_slave_config(sport->dma_chan_tx, &slave_config); > if (ret) { > dev_err(dev, "error in TX dma configuration.");
On Wed, Aug 03, 2022 at 09:15:58AM +0000, Sherry Sun wrote: > > On 03.08.22 08:57, Sherry Sun wrote: > > > Since commit 824a0a02cd74 ("dmaengine: imx-sdma: Add multi fifo > > > support") adds the use of > > > dma_slave_config->peripheral_config/peripheral_size to sdma driver, > > > the client drivers like uart need to initialize the > > > peripheral_config/peripheral_size for sdma, otherwise, the random > > > value of local variable slave_config may cause unexpected > > peripheral_config and make sdma mess up. > > > > > > > If this a fix, please add a Fixes: tag. I am not sure it is though, see below. > > Hi Ahmad, thanks for the comments. > I don't think this patch is a fix for a specific commit, so we don't need the Fixes tag. > > > > > > Signed-off-by: Sherry Sun <sherry.sun@nxp.com> > > > --- > > > drivers/tty/serial/imx.c | 4 ++++ > > > 1 file changed, 4 insertions(+) > > > > > > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index > > > 522445a8f666..bb8c2a712e94 100644 > > > --- a/drivers/tty/serial/imx.c > > > +++ b/drivers/tty/serial/imx.c > > > @@ -1320,6 +1320,8 @@ static int imx_uart_dma_init(struct imx_port > > > *sport) > > > > This function starts with > > > > struct dma_slave_config slave_config = {}; > > > > > slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; > > > /* one byte less than the watermark level to enable the aging timer > > */ > > > slave_config.src_maxburst = RXTL_DMA - 1; > > > + slave_config.peripheral_config = NULL; > > > + slave_config.peripheral_size = 0; > > > > So these are already zero-initialized. > > I am not sure actually, I think initialize a struct with {} cannot guarantee that all members are initialized to 0, it may depend on the compiler. Not true, it's part of the C standard somewhere... thanks, greg k-h
On Wed, Aug 03, 2022 at 09:15:58AM +0000, Sherry Sun wrote: > > On 03.08.22 08:57, Sherry Sun wrote: > > > Since commit 824a0a02cd74 ("dmaengine: imx-sdma: Add multi fifo > > > support") adds the use of > > > dma_slave_config->peripheral_config/peripheral_size to sdma driver, > > > the client drivers like uart need to initialize the > > > peripheral_config/peripheral_size for sdma, otherwise, the random > > > value of local variable slave_config may cause unexpected > > peripheral_config and make sdma mess up. > > > > > > > If this a fix, please add a Fixes: tag. I am not sure it is though, see below. > > Hi Ahmad, thanks for the comments. > I don't think this patch is a fix for a specific commit, so we don't need the Fixes tag. > > > > > > Signed-off-by: Sherry Sun <sherry.sun@nxp.com> > > > --- > > > drivers/tty/serial/imx.c | 4 ++++ > > > 1 file changed, 4 insertions(+) > > > > > > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index > > > 522445a8f666..bb8c2a712e94 100644 > > > --- a/drivers/tty/serial/imx.c > > > +++ b/drivers/tty/serial/imx.c > > > @@ -1320,6 +1320,8 @@ static int imx_uart_dma_init(struct imx_port > > > *sport) > > > > This function starts with > > > > struct dma_slave_config slave_config = {}; > > > > > slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; > > > /* one byte less than the watermark level to enable the aging timer > > */ > > > slave_config.src_maxburst = RXTL_DMA - 1; > > > + slave_config.peripheral_config = NULL; > > > + slave_config.peripheral_size = 0; > > > > So these are already zero-initialized. > > I am not sure actually, I think initialize a struct with {} cannot > guarantee that all members are initialized to 0, it may depend on the > compiler. I'm sure and even reverified in my C book[1]. struct mystruct variable = {}; results in all components being initialized to their default initial value (which is 0 for numbers and NULL for pointers). This works for automatic variables since "Standard C" which should cover everthing that is capable to compile today's kernel. Best regards Uwe [1] C - A Reference Manual, 978-0130895929
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 522445a8f666..bb8c2a712e94 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -1320,6 +1320,8 @@ static int imx_uart_dma_init(struct imx_port *sport) slave_config.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; /* one byte less than the watermark level to enable the aging timer */ slave_config.src_maxburst = RXTL_DMA - 1; + slave_config.peripheral_config = NULL; + slave_config.peripheral_size = 0; ret = dmaengine_slave_config(sport->dma_chan_rx, &slave_config); if (ret) { dev_err(dev, "error in RX dma configuration.\n"); @@ -1346,6 +1348,8 @@ static int imx_uart_dma_init(struct imx_port *sport) slave_config.dst_addr = sport->port.mapbase + URTX0; slave_config.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; slave_config.dst_maxburst = TXTL_DMA; + slave_config.peripheral_config = NULL; + slave_config.peripheral_size = 0; ret = dmaengine_slave_config(sport->dma_chan_tx, &slave_config); if (ret) { dev_err(dev, "error in TX dma configuration.");
Since commit 824a0a02cd74 ("dmaengine: imx-sdma: Add multi fifo support") adds the use of dma_slave_config->peripheral_config/peripheral_size to sdma driver, the client drivers like uart need to initialize the peripheral_config/peripheral_size for sdma, otherwise, the random value of local variable slave_config may cause unexpected peripheral_config and make sdma mess up. Signed-off-by: Sherry Sun <sherry.sun@nxp.com> --- drivers/tty/serial/imx.c | 4 ++++ 1 file changed, 4 insertions(+)