This is a note to let you know that I've just added the patch titled
spi: dw: Fix wrong FIFO level setting for long xfers
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
spi-dw-fix-wrong-fifo-level-setting-for-long-xfers.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 0912aec78122854cc1bd19cb8c09fc5c81ac9faf
Author: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>
Date: Fri Jan 13 21:59:42 2023 +0300
spi: dw: Fix wrong FIFO level setting for long xfers
[ Upstream commit c63b8fd14a7db719f8252038a790638728c4eb66 ]
Due to using the u16 type in the min_t() macros the SPI transfer length
will be cast to word before participating in the conditional statement
implied by the macro. Thus if the transfer length is greater than 64KB the
Tx/Rx FIFO threshold level value will be determined by the leftover of the
truncated after the type-case length. In the worst case it will cause the
dramatical performance drop due to the "Tx FIFO Empty" or "Rx FIFO Full"
interrupts triggered on each xfer word sent/received to/from the bus.
The problem can be easily fixed by specifying the unsigned int type in the
min_t() macros thus preventing the possible data loss.
Fixes: ea11370fffdf ("spi: dw: get TX level without an additional variable")
Reported-by: Sergey Nazarov <Sergey.Nazarov@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230113185942.2516-1-Sergey.Semin@xxxxxxxxxxxxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/spi/spi-dw-core.c b/drivers/spi/spi-dw-core.c
index 99edddf9958b9..c3bfb6c84cab2 100644
--- a/drivers/spi/spi-dw-core.c
+++ b/drivers/spi/spi-dw-core.c
@@ -366,7 +366,7 @@ static void dw_spi_irq_setup(struct dw_spi *dws)
* will be adjusted at the final stage of the IRQ-based SPI transfer
* execution so not to lose the leftover of the incoming data.
*/
- level = min_t(u16, dws->fifo_len / 2, dws->tx_len);
+ level = min_t(unsigned int, dws->fifo_len / 2, dws->tx_len);
dw_writel(dws, DW_SPI_TXFTLR, level);
dw_writel(dws, DW_SPI_RXFTLR, level - 1);
