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

Andy Yan
2014-11-11T14:47:05Z

On 2014年11月11日 22:20, Zubair Lutfullah Kakakhel wrote:
> Hi Andy,
>
> This patch adds the reg-io-width binding.
>
> Hence the binding patch should come before it.
>
do you mean that I should put dts binding patch
before this patch?
> 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.
if the dts undefined it, the val will be 1.
if the dts defined other value except 4 and 1, return -EINVAL
>
> Regards,
> ZubairLK
>
>
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