[PATCH v2] drm: rcar-du: dw-hdmi: Reject modes with a too high clock frequency

[Kieran Bingham]

Hi Laurent,

On 04/12/2018 16:36, Laurent Pinchart wrote:
> Implement a .mode_valid() handler in the R-Car glue layer to reject
> modes with an unsupported clock frequency.

Thank you, I believe my concerns were addressed;
 (and my misunderstandings are now understandings)

> Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas at ideasonboard.com>

Reviewed-by: Kieran Bingham <kieran.bingham+renesas at ideasonboard.com>

> ---
>  drivers/gpu/drm/rcar-du/rcar_dw_hdmi.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> Changes since v1:
> 
> - Add a comment to explain where the limit comes from
> 
> diff --git a/drivers/gpu/drm/rcar-du/rcar_dw_hdmi.c b/drivers/gpu/drm/rcar-du/rcar_dw_hdmi.c
> index 75490a3e0a2a..603bb340e8cf 100644
> --- a/drivers/gpu/drm/rcar-du/rcar_dw_hdmi.c
> +++ b/drivers/gpu/drm/rcar-du/rcar_dw_hdmi.c
> @@ -35,6 +35,20 @@ static const struct rcar_hdmi_phy_params rcar_hdmi_phy_params[] = {
>  	{ ~0UL,      0x0000, 0x0000, 0x0000 },
>  };
>  
> +static enum drm_mode_status
> +rcar_hdmi_mode_valid(struct drm_connector *connector,
> +		     const struct drm_display_mode *mode)
> +{
> +	/*
> +	 * The maximum supported clock frequency is 297 MHz, as shown in the PHY
> +	 * parameters table.
> +	 */
> +	if (mode->clock > 297000)

It's still a bit of a shame that it's not clear that the mode->clock is
expressed in KHz (unless you already know that, which I didn't)
 - but I'll let that slide for now.

--
KB

> +		return MODE_CLOCK_HIGH;
> +
> +	return MODE_OK;
> +}
> +
>  static int rcar_hdmi_phy_configure(struct dw_hdmi *hdmi,
>  				   const struct dw_hdmi_plat_data *pdata,
>  				   unsigned long mpixelclock)
> @@ -59,6 +73,7 @@ static int rcar_hdmi_phy_configure(struct dw_hdmi *hdmi,
>  }
>  
>  static const struct dw_hdmi_plat_data rcar_dw_hdmi_plat_data = {
> +	.mode_valid = rcar_hdmi_mode_valid,
>  	.configure_phy	= rcar_hdmi_phy_configure,
>  };
>  
> 

-- 
Regards
--
Kieran