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@xxxxxxxxxxxxxx>
> ---
> 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
--
Pengutronix e.K. | Lucas Stach |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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