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FROMGIT: drm/mipi-dsi: Reduce driver bloat of mipi_dsi_*_write_seq()
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Through a cooperative effort between Hsin-Yi Wang and Dmitry
Baryshkov, we have realized the dev_err() in the
mipi_dsi_*_write_seq() macros was causing quite a bit of bloat to the
kernel. Let's hoist this call into drm_mipi_dsi.c by adding a "chatty"
version of the functions that includes the print. While doing this,
add a bit more comments to these macros making it clear that they
print errors and also that they return out of _the caller's_ function.

Without any changes to clients this gives a nice savings. Specifically
the macro was inlined and thus the error report call was inlined into
every call to mipi_dsi_dcs_write_seq() and
mipi_dsi_generic_write_seq(). By using a call to a "chatty" function,
the usage is reduced to one call in the chatty function and a function
call at the invoking site.

Building with my build system shows one example:

$ scripts/bloat-o-meter \
  .../before/panel-novatek-nt36672e.ko \
  .../after/panel-novatek-nt36672e.ko
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-4404 (-4404)
Function                                     old     new   delta
nt36672e_1080x2408_60hz_init               10640    6236   -4404
Total: Before=15055, After=10651, chg -29.25%

Note that given the change in location of the print it's harder to
include the "cmd" in the printout for mipi_dsi_dcs_write_seq() since,
theoretically, someone could call the new chatty function with a
zero-size array and it would be illegal to dereference data[0].
There's a printk format to print the whole buffer and this is probably
more useful for debugging anyway. Given that we're doing this for
mipi_dsi_dcs_write_seq(), let's also print the buffer for
mipi_dsi_generic_write_seq() in the error case.

It should be noted that the current consensus of DRM folks is that the
mipi_dsi_*_write_seq() should be deprecated due to the non-intuitive
return behavior. A future patch will formally mark them as deprecated
and provide an alternative.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20240514102056.v5.4.Id15fae80582bc74a0d4f1338987fa375738f45b9@changeid
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240514102056.v5.4.Id15fae80582bc74a0d4f1338987fa375738f45b9@changeid
(cherry picked from commit 3b72490)
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
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@dianders @barni2000
dianders authored and barni2000 committed Jul 25, 2024
1 parent 5de9f5c commit cc89d56
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Showing 2 changed files with 82 additions and 21 deletions.
56 changes: 56 additions & 0 deletions drivers/gpu/drm/drm_mipi_dsi.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -764,6 +764,34 @@ ssize_t mipi_dsi_generic_write(struct mipi_dsi_device *dsi, const void *payload,
}
EXPORT_SYMBOL(mipi_dsi_generic_write);

/**
* mipi_dsi_generic_write_chatty() - mipi_dsi_generic_write() w/ an error log
* @dsi: DSI peripheral device
* @payload: buffer containing the payload
* @size: size of payload buffer
*
* Like mipi_dsi_generic_write() but includes a dev_err()
* call for you and returns 0 upon success, not the number of bytes sent.
*
* Return: 0 on success or a negative error code on failure.
*/
int mipi_dsi_generic_write_chatty(struct mipi_dsi_device *dsi,
const void *payload, size_t size)
{
struct device *dev = &dsi->dev;
ssize_t ret;

ret = mipi_dsi_generic_write(dsi, payload, size);
if (ret < 0) {
dev_err(dev, "sending generic data %*ph failed: %zd\n",
(int)size, payload, ret);
return ret;
}

return 0;
}
EXPORT_SYMBOL(mipi_dsi_generic_write_chatty);

/**
* mipi_dsi_generic_read() - receive data using a generic read packet
* @dsi: DSI peripheral device
Expand Down Expand Up @@ -852,6 +880,34 @@ ssize_t mipi_dsi_dcs_write_buffer(struct mipi_dsi_device *dsi,
}
EXPORT_SYMBOL(mipi_dsi_dcs_write_buffer);

/**
* mipi_dsi_dcs_write_buffer_chatty - mipi_dsi_dcs_write_buffer() w/ an error log
* @dsi: DSI peripheral device
* @data: buffer containing data to be transmitted
* @len: size of transmission buffer
*
* Like mipi_dsi_dcs_write_buffer() but includes a dev_err()
* call for you and returns 0 upon success, not the number of bytes sent.
*
* Return: 0 on success or a negative error code on failure.
*/
int mipi_dsi_dcs_write_buffer_chatty(struct mipi_dsi_device *dsi,
const void *data, size_t len)
{
struct device *dev = &dsi->dev;
ssize_t ret;

ret = mipi_dsi_dcs_write_buffer(dsi, data, len);
if (ret < 0) {
dev_err(dev, "sending dcs data %*ph failed: %zd\n",
(int)len, data, ret);
return ret;
}

return 0;
}
EXPORT_SYMBOL(mipi_dsi_dcs_write_buffer_chatty);

/**
* mipi_dsi_dcs_write() - send DCS write command
* @dsi: DSI peripheral device
Expand Down
47 changes: 26 additions & 21 deletions include/drm/drm_mipi_dsi.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -256,6 +256,8 @@ int mipi_dsi_picture_parameter_set(struct mipi_dsi_device *dsi,

ssize_t mipi_dsi_generic_write(struct mipi_dsi_device *dsi, const void *payload,
size_t size);
int mipi_dsi_generic_write_chatty(struct mipi_dsi_device *dsi,
const void *payload, size_t size);
ssize_t mipi_dsi_generic_read(struct mipi_dsi_device *dsi, const void *params,
size_t num_params, void *data, size_t size);

Expand All @@ -279,6 +281,8 @@ enum mipi_dsi_dcs_tear_mode {

ssize_t mipi_dsi_dcs_write_buffer(struct mipi_dsi_device *dsi,
const void *data, size_t len);
int mipi_dsi_dcs_write_buffer_chatty(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,
Expand Down Expand Up @@ -311,38 +315,39 @@ int mipi_dsi_dcs_get_display_brightness_large(struct mipi_dsi_device *dsi,

/**
* mipi_dsi_generic_write_seq - transmit data using a generic write packet
*
* This macro will print errors for you and will RETURN FROM THE CALLING
* FUNCTION (yes this is non-intuitive) upon error.
*
* @dsi: DSI peripheral device
* @seq: buffer containing the payload
*/
#define mipi_dsi_generic_write_seq(dsi, seq...) \
do { \
static const u8 d[] = { seq }; \
struct device *dev = &dsi->dev; \
ssize_t ret; \
ret = mipi_dsi_generic_write(dsi, d, ARRAY_SIZE(d)); \
if (ret < 0) { \
dev_err(dev, "transmit data failed: %zd\n", ret); \
return ret; \
} \
#define mipi_dsi_generic_write_seq(dsi, seq...) \
do { \
static const u8 d[] = { seq }; \
int ret; \
ret = mipi_dsi_generic_write_chatty(dsi, d, ARRAY_SIZE(d)); \
if (ret < 0) \
return ret; \
} while (0)

/**
* mipi_dsi_dcs_write_seq - transmit a DCS command with payload
*
* This macro will print errors for you and will RETURN FROM THE CALLING
* FUNCTION (yes this is non-intuitive) upon error.
*
* @dsi: DSI peripheral device
* @cmd: Command
* @seq: buffer containing data to be transmitted
*/
#define mipi_dsi_dcs_write_seq(dsi, cmd, seq...) \
do { \
static const u8 d[] = { cmd, seq }; \
struct device *dev = &dsi->dev; \
ssize_t ret; \
ret = mipi_dsi_dcs_write_buffer(dsi, d, ARRAY_SIZE(d)); \
if (ret < 0) { \
dev_err(dev, "sending command %#02x failed: %zd\n", \
cmd, ret); \
return ret; \
} \
#define mipi_dsi_dcs_write_seq(dsi, cmd, seq...) \
do { \
static const u8 d[] = { cmd, seq }; \
int ret; \
ret = mipi_dsi_dcs_write_buffer_chatty(dsi, d, ARRAY_SIZE(d)); \
if (ret < 0) \
return ret; \
} while (0)

/**
Expand Down

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