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

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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@xxxxxxxxxxxxxx>

---

  }
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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