From: Emil Velikov <emil.l.velikov@gmail.com>
To: ML dri-devel <dri-devel@lists.freedesktop.org>
Cc: Jani Nikula <jani.nikula@intel.com>, Thierry Reding <treding@nvidia.com>
Subject: Re: [PATCH 1/3] drm/dsi: use stack buffer in mipi_dsi_dcs_write()
Date: Thu, 28 May 2020 17:47:41 +0100 [thread overview]
Message-ID: <CACvgo53nBpP_cHp=kvBQJnCacdqPfOVxbTf1_x=KhiCyNzbWuQ@mail.gmail.com> (raw)
In-Reply-To: <20200505160329.2976059-1-emil.l.velikov@gmail.com>
On Tue, 5 May 2020 at 17:05, Emil Velikov <emil.l.velikov@gmail.com> wrote:
>
> Currently the function heap allocates when we have any payload. Where in
> many case the payload is 1 byte - ouch.
>
> From casual observation, vast majority of the payloads are smaller than
> 8 bytes - so use a stack array tx[8] to avoid the senseless kmalloc and
> kfree dance.
>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Thierry Reding <treding@nvidia.com>
> Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
> ---
> drivers/gpu/drm/drm_mipi_dsi.c | 20 ++++++++++----------
> 1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
> index 55531895dde6..b96d5b4629d7 100644
> --- a/drivers/gpu/drm/drm_mipi_dsi.c
> +++ b/drivers/gpu/drm/drm_mipi_dsi.c
> @@ -748,26 +748,26 @@ ssize_t mipi_dsi_dcs_write(struct mipi_dsi_device *dsi, u8 cmd,
> {
> ssize_t err;
> size_t size;
> + u8 stack_tx[8];
> u8 *tx;
>
> - if (len > 0) {
> - size = 1 + len;
> -
> + size = 1 + len;
> + if (len > ARRAY_SIZE(stack_tx) - 1) {
> tx = kmalloc(size, GFP_KERNEL);
> if (!tx)
> return -ENOMEM;
> -
> - /* concatenate the DCS command byte and the payload */
> - tx[0] = cmd;
> - memcpy(&tx[1], data, len);
> } else {
> - tx = &cmd;
> - size = 1;
> + tx = stack_tx;
> }
>
> + /* concatenate the DCS command byte and the payload */
> + tx[0] = cmd;
> + if (data)
> + memcpy(&tx[1], data, len);
> +
> err = mipi_dsi_dcs_write_buffer(dsi, tx, size);
>
> - if (len > 0)
> + if (tx != stack_tx)
> kfree(tx);
>
> return err;
> --
Thierry, others - humble ping.
Can you check through the series?
Thanks
Emil
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next prev parent reply other threads:[~2020-05-28 16:50 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-05 16:03 [PATCH 1/3] drm/dsi: use stack buffer in mipi_dsi_dcs_write() Emil Velikov
2020-05-05 16:03 ` [PATCH 2/3] drm/panel: use mipi_dsi_dcs_write_buffer where possible Emil Velikov
2020-05-11 11:28 ` Emil Velikov
2020-06-29 7:46 ` Sam Ravnborg
2020-05-05 16:03 ` [PATCH 3/3] drm/mipi: use dcs write for mipi_dsi_dcs_set_tear_scanline Emil Velikov
2020-05-07 12:29 ` Vinay Simha B N
2020-05-07 16:18 ` Emil Velikov
2020-05-13 9:44 ` Emil Velikov
2020-06-07 16:17 ` Vinay Simha B N
2020-06-05 17:36 ` Thierry Reding
2020-06-29 7:47 ` Sam Ravnborg
2020-05-28 16:47 ` Emil Velikov [this message]
2020-06-05 17:37 ` [PATCH 1/3] drm/dsi: use stack buffer in mipi_dsi_dcs_write() Thierry Reding
2020-06-05 17:26 ` Thierry Reding
2020-06-29 7:46 ` Sam Ravnborg
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