[PATCH v2 01/15] drm/dsi: Make mipi_dsi_dcs_{read, write}() symmetrical
Thierry Reding
thierry.reding at gmail.com
Mon Oct 13 03:16:21 PDT 2014
From: Thierry Reding <treding at nvidia.com>
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.
Signed-off-by: Thierry Reding <treding at nvidia.com>
---
Changes in v2:
- provide mipi_dsi_dcs_write_buffer() for backwards compatibility
drivers/gpu/drm/drm_mipi_dsi.c | 127 +++++++++++++++++++++++++++++-----
drivers/gpu/drm/panel/panel-s6e8aa0.c | 2 +-
include/drm/drm_mipi_dsi.h | 6 +-
3 files changed, 114 insertions(+), 21 deletions(-)
diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index eb6dfe52cab2..1702ffd07986 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -199,33 +199,120 @@ int mipi_dsi_detach(struct mipi_dsi_device *dsi)
EXPORT_SYMBOL(mipi_dsi_detach);
/**
- * 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)
{
- const struct mipi_dsi_host_ops *ops = dsi->host->ops;
struct mipi_dsi_msg msg = {
.channel = dsi->channel,
.tx_buf = data,
.tx_len = len
};
- if (!ops || !ops->transfer)
+ if (!dsi->host->ops || !dsi->host->ops->transfer)
return -ENOSYS;
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;
+ }
+
+ return dsi->host->ops->transfer(dsi->host, &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)
+{
+ struct mipi_dsi_msg msg;
+ ssize_t err;
+ size_t size;
+ u8 *tx;
+
+ if (!dsi->host->ops || !dsi->host->ops->transfer)
+ return -ENOSYS;
+
+ if (len > 0) {
+ unsigned int offset = 0;
+
+ /*
+ * DCS long write packets contain the word count in the header
+ * bytes 1 and 2 and have a payload containing the DCS command
+ * byte folowed by word count minus one bytes.
+ *
+ * DCS short write packets encode the DCS command and up to
+ * one parameter in header bytes 1 and 2.
+ */
+ if (len > 1)
+ size = 3 + len;
+ else
+ size = 1 + len;
+
+ tx = kmalloc(size, GFP_KERNEL);
+ if (!tx)
+ return -ENOMEM;
+
+ /* write word count to header for DCS long write packets */
+ if (len > 1) {
+ tx[offset++] = ((1 + len) >> 0) & 0xff;
+ tx[offset++] = ((1 + len) >> 8) & 0xff;
+ }
+
+ /* write the DCS command byte followed by the payload */
+ tx[offset++] = cmd;
+ memcpy(tx + offset, data, len);
+ } else {
+ tx = &cmd;
+ size = 1;
+ }
+
+ memset(&msg, 0, sizeof(msg));
+ msg.channel = dsi->channel;
+ msg.tx_len = size;
+ msg.tx_buf = tx;
+
+ switch (len) {
+ case 0:
+ msg.type = MIPI_DSI_DCS_SHORT_WRITE;
+ break;
+ case 1:
+ msg.type = MIPI_DSI_DCS_SHORT_WRITE_PARAM;
+ break;
default:
msg.type = MIPI_DSI_DCS_LONG_WRITE;
break;
@@ -234,23 +321,27 @@ ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, const void *data,
if (dsi->mode_flags & MIPI_DSI_MODE_LPM)
msg.flags = MIPI_DSI_MSG_USE_LPM;
- return ops->transfer(dsi->host, &msg);
+ err = dsi->host->ops->transfer(dsi->host, &msg);
+
+ 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)
{
- const struct mipi_dsi_host_ops *ops = dsi->host->ops;
struct mipi_dsi_msg msg = {
.channel = dsi->channel,
.type = MIPI_DSI_DCS_READ,
@@ -260,13 +351,13 @@ ssize_t mipi_dsi_dcs_read(struct mipi_dsi_device *dsi, u8 cmd, void *data,
.rx_len = len
};
- if (!ops || !ops->transfer)
+ if (!dsi->host->ops || !dsi->host->ops->transfer)
return -ENOSYS;
if (dsi->mode_flags & MIPI_DSI_MODE_LPM)
msg.flags = MIPI_DSI_MSG_USE_LPM;
- return ops->transfer(dsi->host, &msg);
+ return dsi->host->ops->transfer(dsi->host, &msg);
}
EXPORT_SYMBOL(mipi_dsi_dcs_read);
diff --git a/drivers/gpu/drm/panel/panel-s6e8aa0.c b/drivers/gpu/drm/panel/panel-s6e8aa0.c
index b5217fe37f02..0f85a7c37687 100644
--- 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, len,
data);
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 8569dc5a1026..ccc3869e137b 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -132,8 +132,10 @@ 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);
--
2.1.2
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