From: Noralf Trønnes <noralf@xxxxxxxxxxx>
MIPI DCS write/set commands have 8 bit parameters except for the
write_memory commands where it depends on the pixel format.
drm_mipi_dbi does currently only support RGB565 which is 16-bit and it
has to make sure that the pixels enters the SPI bus in big endian format
since the MIPI DBI spec doesn't have support for little endian.
drm_mipi_dbi is optimized for DBI interface option 3 which means that the
16-bit bytes are swapped by the upper layer if the SPI bus does not
support 16 bits per word, signified by the swap_bytes member.
In order to support both 16-bit and 24-bit pixel transfers we need a way
to tell the DBI command layer the format of the buffer. Add a
write_memory_bpw member that the upper layer can use to tell how many
bits per word to use for the SPI transfer.
v4:
- Expand the commit message (Dmitry)
Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx>
---
drivers/gpu/drm/drm_mipi_dbi.c | 14 ++++++++++----
include/drm/drm_mipi_dbi.h | 5 +++++
2 files changed, 15 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/drm_mipi_dbi.c b/drivers/gpu/drm/drm_mipi_dbi.c
index fa8aba6dc81c..77f8a828d6e0 100644
--- a/drivers/gpu/drm/drm_mipi_dbi.c
+++ b/drivers/gpu/drm/drm_mipi_dbi.c
@@ -1079,7 +1079,7 @@ static int mipi_dbi_typec1_command_read(struct mipi_dbi *dbi, u8 *cmd,
static int mipi_dbi_typec1_command(struct mipi_dbi *dbi, u8 *cmd,
u8 *parameters, size_t num)
{
- unsigned int bpw = (*cmd == MIPI_DCS_WRITE_MEMORY_START) ? 16 : 8;
+ unsigned int bpw = 8;
int ret;
if (mipi_dbi_command_is_read(dbi, *cmd))
@@ -1091,6 +1091,9 @@ static int mipi_dbi_typec1_command(struct mipi_dbi *dbi, u8 *cmd,
if (ret || !num)
return ret;
+ if (*cmd == MIPI_DCS_WRITE_MEMORY_START)
+ bpw = dbi->write_memory_bpw;
+
return mipi_dbi_spi1_transfer(dbi, 1, parameters, num, bpw);
}
@@ -1184,8 +1187,8 @@ static int mipi_dbi_typec3_command(struct mipi_dbi *dbi, u8 *cmd,
if (ret || !num)
return ret;
- if (*cmd == MIPI_DCS_WRITE_MEMORY_START && !dbi->swap_bytes)
- bpw = 16;
+ if (*cmd == MIPI_DCS_WRITE_MEMORY_START)
+ bpw = dbi->write_memory_bpw;
spi_bus_lock(spi->controller);
gpiod_set_value_cansleep(dbi->dc, 1);
@@ -1256,12 +1259,15 @@ int mipi_dbi_spi_init(struct spi_device *spi, struct mipi_dbi *dbi,
dbi->spi = spi;
dbi->read_commands = mipi_dbi_dcs_read_commands;
+ dbi->write_memory_bpw = 16;
if (dc) {
dbi->command = mipi_dbi_typec3_command;
dbi->dc = dc;
- if (!spi_is_bpw_supported(spi, 16))
+ if (!spi_is_bpw_supported(spi, 16)) {
+ dbi->write_memory_bpw = 8;
dbi->swap_bytes = true;
+ }
} else {
dbi->command = mipi_dbi_typec1_command;
dbi->tx_buf9_len = SZ_16K;
diff --git a/include/drm/drm_mipi_dbi.h b/include/drm/drm_mipi_dbi.h
index e8e0f8d39f3a..b36596efdcc3 100644
--- a/include/drm/drm_mipi_dbi.h
+++ b/include/drm/drm_mipi_dbi.h
@@ -56,6 +56,11 @@ struct mipi_dbi {
*/
struct spi_device *spi;
+ /**
+ * @write_memory_bpw: Bits per word used on a MIPI_DCS_WRITE_MEMORY_START transfer
+ */
+ unsigned int write_memory_bpw;
+
/**
* @dc: Optional D/C gpio.
*/
--
2.45.1
