[PATCH] spi: spi-imx: correctly configure burst length when using dma

[PATCH] spi: spi-imx: correctly configure burst length when using dma

[Benjamin Bigler]

If DMA is used, burst length should be set to the bus width of the DMA.
Otherwise, the SPI hardware will transmit/receive one word per DMA
request.
Since this issue affects both transmission and reception, it cannot be
detected with a loopback test.
Replace magic numbers 512 and 0xfff with MX51_ECSPI_CTRL_MAX_BURST.

Signed-off-by: Benjamin Bigler <benjamin@bigler.one>
Reported-by Stefan Bigler <linux@bigler.io>
Fixes: 15a6af94a277 ("spi: Increase imx51 ecspi burst length based on transfer length")
Link: https://lore.kernel.org/r/8a415902c751cdbb4b20ce76569216ed@mail.infomaniak.com
---
 drivers/spi/spi-imx.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 498e35c8db2c..272bc871a848 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -659,11 +659,18 @@ static int mx51_ecspi_prepare_transfer(struct spi_imx_data *spi_imx,
 		ctrl |= (spi_imx->target_burst * 8 - 1)
 			<< MX51_ECSPI_CTRL_BL_OFFSET;
 	else {
-		if (spi_imx->count >= 512)
-			ctrl |= 0xFFF << MX51_ECSPI_CTRL_BL_OFFSET;
-		else
-			ctrl |= (spi_imx->count * spi_imx->bits_per_word - 1)
+		if (spi_imx->usedma) {
+			ctrl |= (spi_imx->bits_per_word *
+				spi_imx_bytes_per_word(spi_imx->bits_per_word) - 1)
 				<< MX51_ECSPI_CTRL_BL_OFFSET;
+		} else {
+			if (spi_imx->count >= MX51_ECSPI_CTRL_MAX_BURST)
+				ctrl |= (MX51_ECSPI_CTRL_MAX_BURST - 1)
+						<< MX51_ECSPI_CTRL_BL_OFFSET;
+			else
+				ctrl |= (spi_imx->count * spi_imx->bits_per_word - 1)
+						<< MX51_ECSPI_CTRL_BL_OFFSET;
+		}
 	}
 
 	/* set clock speed */
-- 
2.43.0

Re: [PATCH] spi: spi-imx: correctly configure burst length when using dma

[Greg KH]

On Sat, Dec 09, 2023 at 11:23:26PM +0100, Benjamin Bigler wrote:
> If DMA is used, burst length should be set to the bus width of the DMA.
> Otherwise, the SPI hardware will transmit/receive one word per DMA
> request.
> Since this issue affects both transmission and reception, it cannot be
> detected with a loopback test.
> Replace magic numbers 512 and 0xfff with MX51_ECSPI_CTRL_MAX_BURST.
> 
> Signed-off-by: Benjamin Bigler <benjamin@bigler.one>
> Reported-by Stefan Bigler <linux@bigler.io>
> Fixes: 15a6af94a277 ("spi: Increase imx51 ecspi burst length based on transfer length")
> Link: https://lore.kernel.org/r/8a415902c751cdbb4b20ce76569216ed@mail.infomaniak.com
> ---
>  drivers/spi/spi-imx.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- You have marked a patch with a "Fixes:" tag for a commit that is in an
  older released kernel, yet you do not have a cc: stable line in the
  signed-off-by area at all, which means that the patch will not be
  applied to any older kernel releases.  To properly fix this, please
  follow the documented rules in the
  Documentation/process/stable-kernel-rules.rst file for how to resolve
  this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot

Re: [PATCH] spi: spi-imx: correctly configure burst length when using dma

[Mark Brown]

On Sat, 09 Dec 2023 23:23:26 +0100, Benjamin Bigler wrote:
> If DMA is used, burst length should be set to the bus width of the DMA.
> Otherwise, the SPI hardware will transmit/receive one word per DMA
> request.
> Since this issue affects both transmission and reception, it cannot be
> detected with a loopback test.
> Replace magic numbers 512 and 0xfff with MX51_ECSPI_CTRL_MAX_BURST.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: spi-imx: correctly configure burst length when using dma
      commit: e9b220aeacf109684cce36a94fc24ed37be92b05

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark