[PATCH 1/2] drm: Create mipi_dsi_dcs_read_multi()

Brigham Campbell
2025-07-24T20:23:45Z

Create mipi_dsi_dcs_read_multi(), which accepts a mipi_dsi_multi_context
struct for improved error handling and cleaner panel driver code.

Signed-off-by: Brigham Campbell <me@brighamcampbell.com>
---
drivers/gpu/drm/drm_mipi_dsi.c | 37 ++++++++++++++++++++++++++++++++++
include/drm/drm_mipi_dsi.h | 2 ++
2 files changed, 39 insertions(+)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index a00d76443128..227b28555174 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -1075,6 +1075,43 @@ ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *dsi, u8 cmd, void *data,
}
EXPORT_SYMBOL(mipi_dsi_dcs_read);

+/**
+ * mipi_dsi_dcs_read_multi() - mipi_dsi_dcs_read() w/ accum_err
+ * @ctx: Context for multiple DSI transactions
+ * @cmd: DCS command
+ * @data: buffer in which to receive data
+ * @len: size of receive buffer
+ *
+ * Like mipi_dsi_dcs_read() but deals with errors in a way that makes it
+ * convenient to make several calls in a row.
+ */
+void mipi_dsi_dcs_read_multi(struct mipi_dsi_multi_context *ctx, u8 cmd,
+ void *data, size_t len)
+{
+ struct mipi_dsi_device *dsi = ctx->dsi;
+ struct device *dev = &dsi->dev;
+ struct mipi_dsi_msg msg = {
+ .channel = dsi->channel,
+ .type = MIPI_DSI_DCS_READ,
+ .tx_buf = &cmd,
+ .tx_len = 1,
+ .rx_buf = data,
+ .rx_len = len
+ };
+ ssize_t ret;
+
+ if (ctx->accum_err)
+ return;
+
+ ret = mipi_dsi_device_transfer(dsi, &msg);
+ if (ret < 0) {
+ ctx->accum_err = ret;
+ dev_err(dev, "transferring dcs message %xh failed: %d\n", cmd,
+ ctx->accum_err);
+ }
+}
+EXPORT_SYMBOL(mipi_dsi_dcs_read_multi);
+
/**
* mipi_dsi_dcs_nop() - send DCS nop packet
* @dsi: DSI peripheral device
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 369b0d8830c3..d17c00d299c8 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -333,6 +333,8 @@ ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, u8 cmd,
const void *data, size_t len);
ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *dsi, u8 cmd, void *data,
size_t len);
+void mipi_dsi_dcs_read_multi(struct mipi_dsi_multi_context *ctx, u8 cmd,
+ void *data, size_t len);
int mipi_dsi_dcs_nop(struct mipi_dsi_device *dsi);
int mipi_dsi_dcs_soft_reset(struct mipi_dsi_device *dsi);
int mipi_dsi_dcs_get_power_mode(struct mipi_dsi_device *dsi, u8 *mode);
--
2.50.1