Patch "spi: cadence-quadspi: fix incorrect supports_op() return value" has been added to the 5.17-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    spi: cadence-quadspi: fix incorrect supports_op() return value

to the 5.17-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-cadence-quadspi-fix-incorrect-supports_op-return.patch
and it can be found in the queue-5.17 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 297f14d700bc070d21ba9d76cdbbb40165374a01
Author: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx>
Date:   Wed Apr 6 15:28:32 2022 +0200

    spi: cadence-quadspi: fix incorrect supports_op() return value
    
    [ Upstream commit f1d388f216aeb41a5df518815ae559d14a6d438e ]
    
    Since the conversion to spi-mem, the driver advertised support for
    various operations that cqspi_set_protocol() was never expected to handle
    correctly - in particuar all non-DTR operations with command or address
    buswidth > 1. For DTR, all operations except for 8-8-8 would fail, as
    cqspi_set_protocol() returns -EINVAL.
    
    In non-DTR mode, this resulted in data corruption for SPI-NOR flashes that
    support such operations. As a minimal fix that can be backported to stable
    kernels, simply disallow the unsupported operations again to avoid this
    issue.
    
    Fixes: a314f6367787 ("mtd: spi-nor: Convert cadence-quadspi to use spi-mem framework")
    Signed-off-by: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20220406132832.199777-1-matthias.schiffer@xxxxxxxxxxxxxxx
    Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index 75f356041138..b8ac24318cb3 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -1415,9 +1415,24 @@ static bool cqspi_supports_mem_op(struct spi_mem *mem,
 	all_false = !op->cmd.dtr && !op->addr.dtr && !op->dummy.dtr &&
 		    !op->data.dtr;
 
-	/* Mixed DTR modes not supported. */
-	if (!(all_true || all_false))
+	if (all_true) {
+		/* Right now we only support 8-8-8 DTR mode. */
+		if (op->cmd.nbytes && op->cmd.buswidth != 8)
+			return false;
+		if (op->addr.nbytes && op->addr.buswidth != 8)
+			return false;
+		if (op->data.nbytes && op->data.buswidth != 8)
+			return false;
+	} else if (all_false) {
+		/* Only 1-1-X ops are supported without DTR */
+		if (op->cmd.nbytes && op->cmd.buswidth > 1)
+			return false;
+		if (op->addr.nbytes && op->addr.buswidth > 1)
+			return false;
+	} else {
+		/* Mixed DTR modes are not supported. */
 		return false;
+	}
 
 	if (all_true)
 		return spi_mem_dtr_supports_op(mem, op);