spi: spi-imx: correctly configure burst length when using dma

[ Upstream commit e9b220aeacf109684cce36a94fc24ed37be92b05 ]

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.

Reported-by Stefan Bigler <linux@bigler.io>

Signed-off-by: Benjamin Bigler <benjamin@bigler.one>
Fixes: 15a6af94a277 ("spi: Increase imx51 ecspi burst length based on transfer length")
Link: https://lore.kernel.org/r/8a415902c751cdbb4b20ce76569216ed@mail.infomaniak.com
Link: https://lore.kernel.org/r/20231209222338.5564-1-benjamin@bigler.one
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 498e35c..272bc87 100644 (file)
--- 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 */