Re: [PATCH v7 5/7] drm: bridge/dw-hdmi: add support for multi byte register width access

Zubair Lutfullah Kakakhel
2014-11-11T14:20:32Z

Hi Andy,

This patch adds the reg-io-width binding.

Hence the binding patch should come before it.

On 11/11/14 12:53, Andy Yan wrote:
> On rockchip rk3288, only word(32-bit) accesses are
> permitted for hdmi registers. Byte width accesses (writeb,
> readb) generate an imprecise external abort.
>
> Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
>
> ---
>
> }
>
> static void hdmi_modb(struct dw_hdmi *hdmi, u8 data, u8 mask, unsigned reg)
> @@ -1499,6 +1527,23 @@ static int dw_hdmi_bind(struct device *dev, struct device *master, void *data)
> struct device_node *ddc_node;
> struct resource *iores;
> int ret, irq;
> + u32 val = 1;
> +
> + of_property_read_u32(np, "reg-io-width", &val);
> +
> + switch (val) {
> + case 4:
> + hdmi->write = dw_hdmi_writel;
> + hdmi->read = dw_hdmi_readl;
> + break;
> + case 1:
> + hdmi->write = dw_hdmi_writeb;
> + hdmi->read = dw_hdmi_readb;
> + break;
> + default:
> + dev_err(dev, "reg-io-width must be 1 or 4\n");
> + return -EINVAL;
> + }

The binding patch says this is an optional property.
But here if undefined it returns -EINVAL.

I would keep it optional and default it to byte access.

Regards,
ZubairLK