Messages in this thread | | | Date | Thu, 2 May 2024 09:27:46 +0200 | From | Neil Armstrong <> | Subject | Re: [PATCH v3 4/9] drm/mipi-dsi: Reduce driver bloat of mipi_dsi_*_write_seq() |
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On 01/05/2024 17:41, Douglas Anderson wrote: > 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. 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> > Signed-off-by: Douglas Anderson <dianders@chromium.org> > --- > > Changes in v3: > - Rebased upon patch to remove ratelimit of prints. > > Changes in v2: > - Add some comments to the macros about printing and returning. > - Change the way err value is handled in prep for next patch. > - Modify commit message now that this is part of a series. > - Rebased upon patches to avoid theoretical int overflow. > > drivers/gpu/drm/drm_mipi_dsi.c | 56 ++++++++++++++++++++++++++++++++++ > include/drm/drm_mipi_dsi.h | 47 +++++++++++++++------------- > 2 files changed, 82 insertions(+), 21 deletions(-) > > diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c > index 795001bb7ff1..8593d9ed5891 100644 > --- a/drivers/gpu/drm/drm_mipi_dsi.c > +++ b/drivers/gpu/drm/drm_mipi_dsi.c > @@ -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_ratelimited() > + * 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 > @@ -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_ratelimited() > + * 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 > diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h > index 67967be48dbd..6d68d9927f46 100644 > --- a/include/drm/drm_mipi_dsi.h > +++ b/include/drm/drm_mipi_dsi.h > @@ -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); > > @@ -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, > @@ -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) > > /**
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
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