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Message-ID: <300eab2e-f884-4978-9f19-b764bb5fb47a@linaro.org>
Date: Thu, 25 Apr 2024 09:55:11 +0200
From: Neil Armstrong <neil.armstrong@...aro.org>
To: Douglas Anderson <dianders@...omium.org>, dri-devel@...ts.freedesktop.org
Cc: Javier Martinez Canillas <javierm@...hat.com>,
Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, linus.walleij@...aro.org,
Cong Yang <yangcong5@...qin.corp-partner.google.com>,
lvzhaoxiong@...qin.corp-partner.google.com, Hsin-Yi Wang
<hsinyi@...gle.com>, Sam Ravnborg <sam@...nborg.org>,
Daniel Vetter <daniel@...ll.ch>, David Airlie <airlied@...il.com>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/mipi-dsi: Reduce driver bloat of
mipi_dsi_*_write_seq()
On 25/04/2024 02:20, Douglas Anderson wrote:
> The consensus of many DRM folks is that we want to move away from DSI
> drivers defining tables of init commands. Instead, we want to move to
> init functions that can use common DRM functions. The issue thus far
> has been that using the macros mipi_dsi_generic_write_seq() and
> mipi_dsi_dcs_write_seq() bloats the driver using them.
>
> Through a cooperative effort between Hsin-Yi Wang and Dmitry
> Baryshkov, we have realized that the majority of the bloat is the fact
> that we have the dev_err_ratelimited() directly in the macros. Let's
> hoist this call into drm_mipi_dsi.c by adding a "chatty" version of
> the functions that includes the print.
>
> Without any changes to clients this gives a dramatic 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: 0/1 grow/shrink: 1/1 up/down: 6/-19652 (-19646)
> Function old new delta
> __UNIQUE_ID_vermagic520 64 70 +6
> nt36672e_1080x2408_60hz_init 16592 7260 -9332
> nt36672e_1080x2408_60hz_init._rs 10320 - -10320
> Total: Before=31503, After=11857, chg -62.36%
>
> 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.
>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> ---
> The MIPI device I have in front of me (wormdingler) hasn't been
> converted to use these functions yet, so this is just compile
> tested. It's about my end of day so I'm sending this out since it's
> pretty straightforward. Hopefully others can confirm it works well for
> them and also saves space under their compilers.
>
> drivers/gpu/drm/drm_mipi_dsi.c | 54 ++++++++++++++++++++++++++++++++++
> include/drm/drm_mipi_dsi.h | 31 ++++++++-----------
> 2 files changed, 67 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
> index 795001bb7ff1..5ded6aef38ed 100644
> --- a/drivers/gpu/drm/drm_mipi_dsi.c
> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
> @@ -764,6 +764,33 @@ 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
> + *
> + * Just like mipi_dsi_generic_write() but includes a dev_err_ratelimited()
> + * call for you.
> + *
> + * Return: The number of bytes transmitted on success or a negative error code
> + * on failure.
> + */
> +ssize_t mipi_dsi_generic_write_chatty(struct mipi_dsi_device *dsi,
> + const void *payload, size_t size)
> +{
> + struct device *dev = &dsi->dev;
> + int ret;
> +
> + ret = mipi_dsi_generic_write(dsi, payload, size);
> + if (ret < 0)
> + dev_err_ratelimited(dev, "sending generic data %*ph failed: %d\n",
> + (int)size, payload, ret);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(mipi_dsi_generic_write_chatty);
> +
> /**
> * mipi_dsi_generic_read() - receive data using a generic read packet
> * @dsi: DSI peripheral device
> @@ -852,6 +879,33 @@ 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
> + *
> + * Just like mipi_dsi_dcs_write_buffer() but includes a dev_err_ratelimited()
> + * call for you.
> + *
> + * Return: The number of bytes successfully transmitted or a negative error
> + * code on failure.
> + */
> +ssize_t mipi_dsi_dcs_write_buffer_chatty(struct mipi_dsi_device *dsi,
> + const void *data, size_t len)
> +{
> + struct device *dev = &dsi->dev;
> + int ret;
> +
> + ret = mipi_dsi_dcs_write_buffer(dsi, data, len);
> + if (ret < 0)
> + dev_err_ratelimited(dev, "sending dcs data %*ph failed: %d\n",
> + (int)len, data, ret);
> +
> + return ret;
> +}
> +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 82b1cc434ea3..784e425dc4c8 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);
> +ssize_t 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);
> +ssize_t 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,
> @@ -317,14 +321,10 @@ int mipi_dsi_dcs_get_display_brightness_large(struct mipi_dsi_device *dsi,
> #define mipi_dsi_generic_write_seq(dsi, seq...) \
> do { \
> static const u8 d[] = { seq }; \
> - struct device *dev = &dsi->dev; \
> int ret; \
> - ret = mipi_dsi_generic_write(dsi, d, ARRAY_SIZE(d)); \
> - if (ret < 0) { \
> - dev_err_ratelimited(dev, "transmit data failed: %d\n", \
> - ret); \
> + ret = mipi_dsi_generic_write_chatty(dsi, d, ARRAY_SIZE(d)); \
> + if (ret < 0) \
> return ret; \
> - } \
> } while (0)
>
> /**
> @@ -333,18 +333,13 @@ int mipi_dsi_dcs_get_display_brightness_large(struct mipi_dsi_device *dsi,
> * @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; \
> - int ret; \
> - ret = mipi_dsi_dcs_write_buffer(dsi, d, ARRAY_SIZE(d)); \
> - if (ret < 0) { \
> - dev_err_ratelimited( \
> - dev, "sending command %#02x failed: %d\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)
>
> /**
At first sight it looks o for me, it's less efficient since it adds a function call
for each sequence, but the saving if very significant.
I'll run a test on the vtdr6130 to be sure.
Neil
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