Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 7eef3b46 authored by Paul Cercueil's avatar Paul Cercueil Committed by Greg Kroah-Hartman
Browse files

drm/dbi: Fix SPI Type 1 (9-bit) transfer 



commit 900ab59e2621053b009f707f80b2c19ce0af5dee upstream.

The function mipi_dbi_spi1_transfer() will transfer its payload as 9-bit
data, the 9th (MSB) bit being the data/command bit. In order to do that,
it unpacks the 8-bit values into 16-bit values, then sets the 9th bit if
the byte corresponds to data, clears it otherwise. The 7 MSB are
padding. The array of now 16-bit values is then passed to the SPI core
for transfer.

This function was broken since its introduction, as the length of the
SPI transfer was set to the payload size before its conversion, but the
payload doubled in size due to the 8-bit -> 16-bit conversion.

Fixes: 02dd95fe ("drm/tinydrm: Add MIPI DBI support")
Cc: <stable@vger.kernel.org> # 5.4+
Signed-off-by: default avatarPaul Cercueil <paul@crapouillou.net>
Reviewed-by: default avatarSam Ravnborg <sam@ravnborg.org>
Reviewed-by: default avatarNoralf Trønnes <noralf@tronnes.org>
Signed-off-by: default avatarSam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200703141341.1266263-1-paul@crapouillou.net


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 8ea180f1

drivers/gpu/drm/drm_mipi_dbi.c

+1 −1
Original line number Diff line number Diff line
@@ -937,7 +937,7 @@ static int mipi_dbi_spi1_transfer(struct mipi_dbi *dbi, int dc, 
			}

		}



		tr.len = chunk;

		tr.len = chunk * 2;

		len -= chunk;



		ret = spi_sync(spi, &m);