This is a note to let you know that I've just added the patch titled
spi: rockchip: handle zero length transfers without timing out
to the 5.14-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-rockchip-handle-zero-length-transfers-without-ti.patch
and it can be found in the queue-5.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b7af367bf19005467fa6819176274c215d0dca16
Author: Tobias Schramm <t.schramm@xxxxxxxxxxx>
Date: Fri Aug 27 07:03:57 2021 +0200
spi: rockchip: handle zero length transfers without timing out
[ Upstream commit 5457773ef99f25fcc4b238ac76b68e28273250f4 ]
Previously zero length transfers submitted to the Rokchip SPI driver would
time out in the SPI layer. This happens because the SPI peripheral does
not trigger a transfer completion interrupt for zero length transfers.
Fix that by completing zero length transfers immediately at start of
transfer.
Signed-off-by: Tobias Schramm <t.schramm@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20210827050357.165409-1-t.schramm@xxxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index 540861ca2ba3..553b6b9d0222 100644
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -600,6 +600,12 @@ static int rockchip_spi_transfer_one(
int ret;
bool use_dma;
+ /* Zero length transfers won't trigger an interrupt on completion */
+ if (!xfer->len) {
+ spi_finalize_current_transfer(ctlr);
+ return 1;
+ }
+
WARN_ON(readl_relaxed(rs->regs + ROCKCHIP_SPI_SSIENR) &&
(readl_relaxed(rs->regs + ROCKCHIP_SPI_SR) & SR_BUSY));
