On Thu, May 28, 2020 at 05:47:41PM +0100, Emil Velikov wrote:
> On Tue, 5 May 2020 at 17:05, Emil Velikov <emil.l.velikov@xxxxxxxxx> 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@xxxxxxxxx>
> > Cc: Thierry Reding <treding@xxxxxxxxxx>
> > Signed-off-by: Emil Velikov <emil.velikov@xxxxxxxxxxxxx>
> > ---
> > 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?
I don't see patch 2 of this series anywhere? Did it fall victim to some
filter?
Thierry
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