Re: [PATCH 2/7] drm/omap: tweak HDMI DDC timings

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Tomi,

Thank you for the path.

On Mon, Sep 02, 2019 at 03:53:54PM +0300, Tomi Valkeinen wrote:
> From: Alejandro Hernandez <ajhernandez@ti.com>
> 
> A "HDMI I2C Master Error" is sometimes reported with the current DDC SCL
> timings. The current settings for a 10us SCL period (100 KHz) causes the
> error with some displays.  This patch increases the SCL signal period
> from 10us to 10.2us, with the new settings the error is not observed
> 

It would be useful to document what those "some displays" are if you
can.

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> Signed-off-by: Alejandro Hernandez <ajhernandez@ti.com>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> ---
>  drivers/gpu/drm/omapdrm/dss/hdmi5_core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/omapdrm/dss/hdmi5_core.c b/drivers/gpu/drm/omapdrm/dss/hdmi5_core.c
> index 7400fb99d453..4c588ec7634a 100644
> --- a/drivers/gpu/drm/omapdrm/dss/hdmi5_core.c
> +++ b/drivers/gpu/drm/omapdrm/dss/hdmi5_core.c
> @@ -39,8 +39,8 @@ static void hdmi_core_ddc_init(struct hdmi_core_data *core)
>  {
>  	void __iomem *base = core->base;
>  	const unsigned long long iclk = 266000000;	/* DSS L3 ICLK */
> -	const unsigned int ss_scl_high = 4600;		/* ns */
> -	const unsigned int ss_scl_low = 5400;		/* ns */
> +	const unsigned int ss_scl_high = 4700;		/* ns */
> +	const unsigned int ss_scl_low = 5500;		/* ns */
>  	const unsigned int fs_scl_high = 600;		/* ns */
>  	const unsigned int fs_scl_low = 1300;		/* ns */
>  	const unsigned int sda_hold = 1000;		/* ns */

-- 
Regards,

Laurent Pinchart
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