[PATCH] tty: serial: imx: initialize peripheral_config/peripheral_size for sdma config

[PATCH] tty: serial: imx: initialize peripheral_config/peripheral_size for sdma config

[Sherry Sun]

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(+)

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.");
-- 
2.17.1

Re: [PATCH] tty: serial: imx: initialize peripheral_config/peripheral_size for sdma config

[Ahmad Fatoum]

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.");


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RE: [PATCH] tty: serial: imx: initialize peripheral_config/peripheral_size for sdma config

[Sherry Sun]

> 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.

Best regards
Sherry

> 
> >  	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.
> 

Re: [PATCH] tty: serial: imx: initialize peripheral_config/peripheral_size for sdma config

[gregkh]

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

RE: [PATCH] tty: serial: imx: initialize peripheral_config/peripheral_size for sdma config

[Sherry Sun]

> 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...
>

Hi Greg, okay, thanks for the confirmation!
Then I think this patch is not needed any more. ^_^

Best regards
Sherry

Re: [PATCH] tty: serial: imx: initialize peripheral_config/peripheral_size for sdma config

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 2369 bytes --]

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

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

RE: [PATCH] tty: serial: imx: initialize peripheral_config/peripheral_size for sdma config

[Sherry Sun]

> Subject: Re: [PATCH] tty: serial: imx: initialize
> peripheral_config/peripheral_size for sdma config
> 
> 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
> 

Hi Uwe, wow, this really resolved my confusion, thanks a lot for your confirmation! ^_^

Best regards
Sherry