drm/mipi-dsi: Introduce mipi_dsi_*_write_seq_multi()

The current mipi_dsi_*_write_seq() macros are non-intutitive because
they contain a hidden "return" statement that will return out of the
_caller_ of the macro. Let's mark them as deprecated and instead
introduce some new macros that are more intuitive.

These new macros are less optimal when an error occurs but should
behave more optimally when there is no error. Specifically these new
macros cause smaller code to get generated and the code size savings
(less to fetch from RAM, less cache space used, less RAM used) are
important. Since the error case isn't something we need to optimize
for and these new macros are easier to understand and more flexible,
they should be used.

After converting to use these new functions, one example shows some
nice savings while also being easier to understand.

$ scripts/bloat-o-meter \
  ...after/panel-novatek-nt36672e.ko \
  ...ctx/panel-novatek-nt36672e.ko
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-988 (-988)
Function                                     old     new   delta
nt36672e_1080x2408_60hz_init                6236    5248    -988
Total: Before=10651, After=9663, chg -9.28%

Reviewed-by: Neil Armstrong <[email protected]>
Reviewed-by: Linus Walleij <[email protected]>
Signed-off-by: Douglas Anderson <[email protected]>
Link: https://lore.kernel.org/r/20240514102056.v5.5.Ie94246c30fe95101e0e26dd5f96e976dbeb8f242@changeid
Signed-off-by: Neil Armstrong <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/20240514102056.v5.5.Ie94246c30fe95101e0e26dd5f96e976dbeb8f242@changeid

1 files changed, 56 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index 4d2685d5a6e0..26c7383406c1 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -793,6 +793,34 @@ int mipi_dsi_generic_write_chatty(struct mipi_dsi_device *dsi,
 EXPORT_SYMBOL(mipi_dsi_generic_write_chatty);
 
 /**
+ * mipi_dsi_generic_write_multi() - mipi_dsi_generic_write_chatty() w/ accum_err
+ * @ctx: Context for multiple DSI transactions
+ * @payload: buffer containing the payload
+ * @size: size of payload buffer
+ *
+ * Like mipi_dsi_generic_write_chatty() but deals with errors in a way that
+ * makes it convenient to make several calls in a row.
+ */
+void mipi_dsi_generic_write_multi(struct mipi_dsi_multi_context *ctx,
+				  const void *payload, size_t size)
+{
+	struct mipi_dsi_device *dsi = ctx->dsi;
+	struct device *dev = &dsi->dev;
+	ssize_t ret;
+
+	if (ctx->accum_err)
+		return;
+
+	ret = mipi_dsi_generic_write(dsi, payload, size);
+	if (ret < 0) {
+		ctx->accum_err = ret;
+		dev_err(dev, "sending generic data %*ph failed: %d\n",
+			(int)size, payload, ctx->accum_err);
+	}
+}
+EXPORT_SYMBOL(mipi_dsi_generic_write_multi);
+
+/**
  * mipi_dsi_generic_read() - receive data using a generic read packet
  * @dsi: DSI peripheral device
  * @params: buffer containing the request parameters
@@ -909,6 +937,34 @@ int mipi_dsi_dcs_write_buffer_chatty(struct mipi_dsi_device *dsi,
 EXPORT_SYMBOL(mipi_dsi_dcs_write_buffer_chatty);
 
 /**
+ * mipi_dsi_dcs_write_buffer_multi - mipi_dsi_dcs_write_buffer_chatty() w/ accum_err
+ * @ctx: Context for multiple DSI transactions
+ * @data: buffer containing data to be transmitted
+ * @len: size of transmission buffer
+ *
+ * Like mipi_dsi_dcs_write_buffer_chatty() but deals with errors in a way that
+ * makes it convenient to make several calls in a row.
+ */
+void mipi_dsi_dcs_write_buffer_multi(struct mipi_dsi_multi_context *ctx,
+				     const void *data, size_t len)
+{
+	struct mipi_dsi_device *dsi = ctx->dsi;
+	struct device *dev = &dsi->dev;
+	ssize_t ret;
+
+	if (ctx->accum_err)
+		return;
+
+	ret = mipi_dsi_dcs_write_buffer(dsi, data, len);
+	if (ret < 0) {
+		ctx->accum_err = ret;
+		dev_err(dev, "sending dcs data %*ph failed: %d\n",
+			(int)len, data, ctx->accum_err);
+	}
+}
+EXPORT_SYMBOL(mipi_dsi_dcs_write_buffer_multi);
+
+/**
  * mipi_dsi_dcs_write() - send DCS write command
  * @dsi: DSI peripheral device
  * @cmd: DCS command