On 2014年11月07日 19:45, Lucas Stach wrote:
Am Freitag, den 07.11.2014, 19:35 +0800 schrieb Andy Yan:
On rockchip rk3288, only word(32-bit) accesses are
permitted for hdmi registers. Byte width access (writeb,
readb) generates an imprecise external abort.
Signed-off-by: Andy Yan <andy....@rock-chips.com>
---
drivers/gpu/drm/bridge/dw_hdmi.c | 49 +++++++++++++++++++++++++++++++++++++---
1 file changed, 46 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/bridge/dw_hdmi.c b/drivers/gpu/drm/bridge/dw_hdmi.c
index df76a8c..9867642 100644
--- a/drivers/gpu/drm/bridge/dw_hdmi.c
+++ b/drivers/gpu/drm/bridge/dw_hdmi.c
@@ -126,19 +126,42 @@ struct dw_hdmi {
[...]
+ u32 val;
+
+ if (!of_property_read_u32(np, "reg-io-width", &val)) {
+ switch (val) {
+ case 4:
+ hdmi->write = dw_hdmi_writel;
+ hdmi->read = dw_hdmi_readl;
+ hdmi->reg_shift = 2;
+ break;
+ default:
+ hdmi->write = dw_hdmi_writeb;
+ hdmi->read = dw_hdmi_readb;
+ hdmi->reg_shift = 0;
+ break;
+ }
+ } else {
+ hdmi->write = dw_hdmi_writeb;
+ hdmi->read = dw_hdmi_readb;
+ hdmi->reg_shift = 0;
+ }
ddc_node = of_parse_phandle(np, "ddc-i2c-bus", 0);
if (ddc_node) {
This should throw an error if the property value in devicetree is not
recognized. This could be simplified like this:
u32 val = 1;
// this won't touch val if it can't find the property
of_property_read_u32(np, "reg-io-width", &val)
switch (val) {
case 4:
hdmi->write = dw_hdmi_writel;
hdmi->read = dw_hdmi_readl;
hdmi->reg_shift = 2;
break;
case 1:
hdmi->write = dw_hdmi_writeb;
hdmi->read = dw_hdmi_readb;
hdmi->reg_shift = 0;
break;
default:
dev_err(dev, "unrecognized value for reg-io-width");
// error handling
}
Also the DT binding doc for this property is missing.
Regards,
Lucas
thanks for your suggestion, I will take it.
this properity is optional, I will add it to DT binding doc
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