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Date: Sat, 08 Nov 2014 11:19:42 +0800 From: Andy Yan <andy.yan@...k-chips.com> To: Lucas Stach <l.stach@...gutronix.de> CC: airlied@...ux.ie, heiko@...ech.de, fabio.estevam@...escale.com, rmk+kernel@....linux.org.uk, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Grant Likely <grant.likely@...aro.org>, Rob Herring <robh+dt@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>, Shawn Guo <shawn.guo@...aro.org>, Josh Boyer <jwboyer@...hat.com>, Sean Paul <seanpaul@...omium.org>, Inki Dae <inki.dae@...sung.com>, Dave Airlie <airlied@...hat.com>, Arnd Bergmann <arnd@...db.de>, Zubair.Kakakhel@...tec.com, djkurtz@...gle.com, ykk@...k-chips.com, linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org, devel@...verdev.osuosl.org, devicetree@...r.kernel.org, linux-rockchip@...ts.infradead.org, jay.xu@...k-chips.com Subject: Re: [PATCH V4 5/6] dw-hdmi: add support for multi byte register width access 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@...k-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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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