In __spi_validate, there's a validation that no partial transfers
are accepted (xfer->len % w_size must be zero). When
max_chunk is not a multiple of bpw (e.g. max_chunk = 65535,
bpw = 16), the transfer will be rejected.
This patch aligns max_chunk to 2 bytes (the maximum value of bpw is 16),
so that no partial transfer will occur.
Fixes: d23d4d4dac01 ("drm/tinydrm: Move tinydrm_spi_transfer()")
Signed-off-by: Yunhao Tian <t123yh.xyz@xxxxxxxxx>
---
drivers/gpu/drm/drm_mipi_dbi.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/gpu/drm/drm_mipi_dbi.c b/drivers/gpu/drm/drm_mipi_dbi.c
index 71b646c4131f..00d470ff071d 100644
--- a/drivers/gpu/drm/drm_mipi_dbi.c
+++ b/drivers/gpu/drm/drm_mipi_dbi.c
@@ -1183,6 +1183,13 @@ int mipi_dbi_spi_transfer(struct spi_device *spi, u32 speed_hz,
size_t chunk;
int ret;
+ /* In __spi_validate, there's a validation that no partial transfers
+ * are accepted (xfer->len % w_size must be zero).
+ * Here we align max_chunk to multiple of 2 (16bits),
+ * to prevent transfers from being rejected.
+ */
+ max_chunk = ALIGN_DOWN(max_chunk, 2);
+
spi_message_init_with_transfers(&m, &tr, 1);
while (len) {
--
2.25.1
