5.4-stable review patch. If anyone has any objections, please let me know.
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From: Niklas Cassel cassel@kernel.org
[ Upstream commit 91ec84f8eaddbc93d7c62e363d68aeb7b89879c7 ]
atapi_eh_request_sense() currently uses ATAPI DMA if the SATA controller has ATA_FLAG_PIO_DMA (PIO cmds via DMA) set.
However, ATA_FLAG_PIO_DMA is a flag that can be set by a low-level driver on a port at initialization time, before any devices are scanned.
If a controller detects a connected device that only supports PIO, we set the flag ATA_DFLAG_PIO.
Modify atapi_eh_request_sense() to not use ATAPI DMA if the connected device only supports PIO.
Reported-by: Philip Pemberton lists@philpem.me.uk Closes: https://lore.kernel.org/linux-ide/c6722ee8-5e21-4169-af59-cbbae9edc02f@philp... Tested-by: Philip Pemberton lists@philpem.me.uk Reviewed-by: Damien Le Moal dlemoal@kernel.org Link: https://lore.kernel.org/r/20250221015422.20687-2-cassel@kernel.org Signed-off-by: Niklas Cassel cassel@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/ata/libata-eh.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c index fa3f08ca5f6ce..4677eaf737141 100644 --- a/drivers/ata/libata-eh.c +++ b/drivers/ata/libata-eh.c @@ -1603,8 +1603,15 @@ unsigned int atapi_eh_request_sense(struct ata_device *dev, tf.flags |= ATA_TFLAG_ISADDR | ATA_TFLAG_DEVICE; tf.command = ATA_CMD_PACKET;
- /* is it pointless to prefer PIO for "safety reasons"? */ - if (ap->flags & ATA_FLAG_PIO_DMA) { + /* + * Do not use DMA if the connected device only supports PIO, even if the + * port prefers PIO commands via DMA. + * + * Ideally, we should call atapi_check_dma() to check if it is safe for + * the LLD to use DMA for REQUEST_SENSE, but we don't have a qc. + * Since we can't check the command, perhaps we should only use pio? + */ + if ((ap->flags & ATA_FLAG_PIO_DMA) && !(dev->flags & ATA_DFLAG_PIO)) { tf.protocol = ATAPI_PROT_DMA; tf.feature |= ATAPI_PKT_DMA; } else {