[Intel-gfx] [PATCH] KMS: do a faster EDID

[Dave Airlie]

On Tue, Mar 24, 2009 at 6:48 AM, Arjan van de Ven <arjan at infradead.org> wrote:
> >From a121507f31e37a809dfa21c9756aa83f36d7acbf Mon Sep 17 00:00:00 2001
> From: Arjan van de Ven <arjan at linux.intel.com>
> Date: Mon, 23 Mar 2009 13:37:20 -0700
> Subject: [PATCH] KMS: do a faster EDID
>
> for some outputs (like LVDS), the current delays in the EDID reader are way
> overkill.
>
> This patch makes the EDID reader try twice; first with a 5x faster probe, and
> if that fails, it probes at the current speed. This reduces probe time on my LVDS
> panel significantly.

TBH I'd do DDC the first time with none of the setup crap in it.

Just call the DDC function.

If that fails then I'd go through all the sleeping path, which is mainly
for some bonghit monitors from the 90s.

So like the idea but I'd take it further.

Dave.

>
> Signed-off-by: Arjan van de Ven <arjan at linux.intel.com>
> ---
>  drivers/gpu/drm/drm_edid.c |   22 +++++++++++++---------
>  1 files changed, 13 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index a839a28..069b189 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -588,20 +588,22 @@ static unsigned char *drm_ddc_read(struct i2c_adapter *adapter)
>  {
>        struct i2c_algo_bit_data *algo_data = adapter->algo_data;
>        unsigned char *edid = NULL;
> +       int divider = 5;
>        int i, j;
>
>        algo_data->setscl(algo_data->data, 1);
>
> -       for (i = 0; i < 1; i++) {
> +       for (i = 0; i < 2; i++) {
>                /* For some old monitors we need the
>                 * following process to initialize/stop DDC
>                 */
> +
>                algo_data->setsda(algo_data->data, 1);
> -               msleep(13);
> +               msleep(13 / divider);
>
>                algo_data->setscl(algo_data->data, 1);
>                for (j = 0; j < 5; j++) {
> -                       msleep(10);
> +                       msleep(10 / divider);
>                        if (algo_data->getscl(algo_data->data))
>                                break;
>                }
> @@ -609,31 +611,33 @@ static unsigned char *drm_ddc_read(struct i2c_adapter *adapter)
>                        continue;
>
>                algo_data->setsda(algo_data->data, 0);
> -               msleep(15);
> +               msleep(15 / divider);
>                algo_data->setscl(algo_data->data, 0);
> -               msleep(15);
> +               msleep(15  / divider);
>                algo_data->setsda(algo_data->data, 1);
> -               msleep(15);
> +               msleep(15 / divider);
>
>                /* Do the real work */
>                edid = drm_do_probe_ddc_edid(adapter);
>                algo_data->setsda(algo_data->data, 0);
>                algo_data->setscl(algo_data->data, 0);
> -               msleep(15);
> +               msleep(15 / divider);
>
>                algo_data->setscl(algo_data->data, 1);
>                for (j = 0; j < 10; j++) {
> -                       msleep(10);
> +                       msleep(10 / divider);
>                        if (algo_data->getscl(algo_data->data))
>                                break;
>                }
>
>                algo_data->setsda(algo_data->data, 1);
> -               msleep(15);
> +               msleep(15 / divider);
>                algo_data->setscl(algo_data->data, 0);
>                algo_data->setsda(algo_data->data, 0);
> +
>                if (edid)
>                        break;
> +               divider = 1;
>        }
>        /* Release the DDC lines when done or the Apple Cinema HD display
>         * will switch off
> --
> 1.6.0.6
>
>
>
>
> --
> Arjan van de Ven        Intel Open Source Technology Centre
> For development, discussion and tips for power savings,
> visit http://www.lesswatts.org
>
> ------------------------------------------------------------------------------
> Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are
> powering Web 2.0 with engaging, cross-platform capabilities. Quickly and
> easily build your RIAs with Flex Builder, the Eclipse(TM)based development
> software that enables intelligent coding and step-through debugging.
> Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com
> --
> _______________________________________________
> Dri-devel mailing list
> Dri-devel at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/dri-devel
>