drm/dsi: Make mipi_dsi_dcs_{read,write}() symmetrical

Currently the mipi_dsi_dcs_write() function requires the DCS command
byte to be embedded within the write buffer whereas mipi_dsi_dcs_read()
has a separate parameter. Make them more symmetrical by adding an extra
command parameter to mipi_dsi_dcs_write().

The S6E8AA0 driver relies on the old asymmetric API and there's concern
that moving to the new API may be less efficient. Provide a new function
with the old semantics for those cases and make the S6E8AA0 driver use
it instead.

Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index 0cc030a..388c3ab 100644 (file)
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -333,13 +333,19 @@ int mipi_dsi_create_packet(struct mipi_dsi_packet *packet,
 EXPORT_SYMBOL(mipi_dsi_create_packet);
 
 /**
- * mipi_dsi_dcs_write - send DCS write command
- * @dsi: DSI device
- * @data: pointer to the command followed by parameters
- * @len: length of @data
+ * mipi_dsi_dcs_write_buffer() - transmit a DCS command with payload
+ * @dsi: DSI peripheral device
+ * @data: buffer containing data to be transmitted
+ * @len: size of transmission buffer
+ *
+ * This function will automatically choose the right data type depending on
+ * the command payload length.
+ *
+ * Return: The number of bytes successfully transmitted or a negative error
+ * code on failure.
  */
-ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, const void *data,
-                           size_t len)
+ssize_t mipi_dsi_dcs_write_buffer(struct mipi_dsi_device *dsi,
+                                 const void *data, size_t len)
 {
        struct mipi_dsi_msg msg = {
                .channel = dsi->channel,
@@ -350,12 +356,15 @@ ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, const void *data,
        switch (len) {
        case 0:
                return -EINVAL;
+
        case 1:
                msg.type = MIPI_DSI_DCS_SHORT_WRITE;
                break;
+
        case 2:
                msg.type = MIPI_DSI_DCS_SHORT_WRITE_PARAM;
                break;
+
        default:
                msg.type = MIPI_DSI_DCS_LONG_WRITE;
                break;
@@ -363,16 +372,60 @@ ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, const void *data,
 
        return mipi_dsi_device_transfer(dsi, &msg);
 }
+EXPORT_SYMBOL(mipi_dsi_dcs_write_buffer);
+
+/**
+ * mipi_dsi_dcs_write() - send DCS write command
+ * @dsi: DSI peripheral device
+ * @cmd: DCS command
+ * @data: buffer containing the command payload
+ * @len: command payload length
+ *
+ * This function will automatically choose the right data type depending on
+ * the command payload length.
+ *
+ * Return: The number of bytes successfully transmitted or a negative error
+ * code on failure.
+ */
+ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, u8 cmd,
+                          const void *data, size_t len)
+{
+       ssize_t err;
+       size_t size;
+       u8 *tx;
+
+       if (len > 0) {
+               size = 1 + len;
+
+               tx = kmalloc(size, GFP_KERNEL);
+               if (!tx)
+                       return -ENOMEM;
+
+               /* concatenate the DCS command byte and the payload */
+               tx[0] = cmd;
+               memcpy(&tx[1], data, len);
+       } else {
+               tx = &cmd;
+               size = 1;
+       }
+
+       err = mipi_dsi_dcs_write_buffer(dsi, tx, size);
+
+       if (len > 0)
+               kfree(tx);
+
+       return err;
+}
 EXPORT_SYMBOL(mipi_dsi_dcs_write);
 
 /**
- * mipi_dsi_dcs_read - send DCS read request command
- * @dsi: DSI device
- * @cmd: DCS read command
- * @data: pointer to read buffer
- * @len: length of @data
+ * mipi_dsi_dcs_read() - send DCS read request command
+ * @dsi: DSI peripheral device
+ * @cmd: DCS command
+ * @data: buffer in which to receive data
+ * @len: size of receive buffer
  *
- * Function returns number of read bytes or error code.
+ * Return: The number of bytes read or a negative error code on failure.
  */
 ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *dsi, u8 cmd, void *data,
                          size_t len)

diff --git a/drivers/gpu/drm/panel/panel-s6e8aa0.c b/drivers/gpu/drm/panel/panel-s6e8aa0.c
index 96f4476..17bc799 100644 (file)
--- a/drivers/gpu/drm/panel/panel-s6e8aa0.c
+++ b/drivers/gpu/drm/panel/panel-s6e8aa0.c
@@ -141,7 +141,7 @@ static void s6e8aa0_dcs_write(struct s6e8aa0 *ctx, const void *data, size_t len)
        if (ctx->error < 0)
                return;
 
-       ret = mipi_dsi_dcs_write(dsi, data, len);
+       ret = mipi_dsi_dcs_write_buffer(dsi, data, len);
        if (ret < 0) {
                dev_err(ctx->dev, "error %zd writing dcs seq: %*ph\n", ret,
                        (int)len, data);

diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 6e3e3aa..44cece9 100644 (file)
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -153,8 +153,10 @@ static inline struct mipi_dsi_device *to_mipi_dsi_device(struct device *dev)
 
 int mipi_dsi_attach(struct mipi_dsi_device *dsi);
 int mipi_dsi_detach(struct mipi_dsi_device *dsi);
-ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, const void *data,
-                           size_t len);
+ssize_t mipi_dsi_dcs_write_buffer(struct mipi_dsi_device *dsi,
+                                 const void *data, size_t len);
+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);