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.yan@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