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Date: Fri, 28 Nov 2014 17:43:21 +0800
From: Andy Yan <andy.yan@...k-chips.com>
To: Philipp Zabel <p.zabel@...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>,
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>,
Lucas Stach <l.stach@...gutronix.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,
Pawel Moll <pawel.moll@....com>, mark.yao@...k-chips.com,
Mark Rutland <mark.rutland@....com>,
Ian Campbell <ijc+devicetree@...lion.org.uk>,
Kumar Gala <galak@...eaurora.org>
Subject: Re: [PATCH v13 07/12] drm: bridge/dw_hdmi: add support for multi-byte
register width access
Hi Zabel:
On 2014年11月27日 00:34, Philipp Zabel wrote:
> Am Mittwoch, den 26.11.2014, 21:32 +0800 schrieb Andy Yan:
>> 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@...k-chips.com>
>>
>> ---
>>
>> Changes in v13: None
>> Changes in v12: None
>> Changes in v11: None
>> Changes in v10: None
>> Changes in v9: None
>> Changes in v8: None
>> Changes in v7: None
>> Changes in v6:
>> - refactor register access without reg_shift
>>
>> Changes in v5:
>> - refactor reg-io-width
>>
>> Changes in v4: None
>> Changes in v3:
>> - split multi-register access to one indepent patch
>>
>> drivers/gpu/drm/bridge/dw_hdmi.c | 57 +++++++++++++++++++++++++++++++++++-----
>> 1 file changed, 51 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/dw_hdmi.c b/drivers/gpu/drm/bridge/dw_hdmi.c
>> index a53bf63..5e88c8d 100644
>> --- a/drivers/gpu/drm/bridge/dw_hdmi.c
>> +++ b/drivers/gpu/drm/bridge/dw_hdmi.c
>> @@ -100,6 +100,11 @@ struct hdmi_data_info {
>> struct hdmi_vmode video_mode;
>> };
>>
>> +union dw_reg_ptr {
>> + u32 __iomem *p32;
>> + u8 __iomem *p8;
>> +};
> I see no need to introduce this. Just explicitly multiply the offset in
> dw_hdmi_writel.
>
Is there any disadvantage to do like this?
The compiler can help us do the explicitly multiply by this way.
>> struct dw_hdmi {
>> struct drm_connector connector;
>> struct drm_encoder *encoder;
>> @@ -121,20 +126,43 @@ struct dw_hdmi {
>>
>> struct regmap *regmap;
>> struct i2c_adapter *ddc;
>> - void __iomem *regs;
>> + union dw_reg_ptr regs;
> Keep this as void __iomem *
>
>> unsigned int sample_rate;
>> int ratio;
>> +
>> + void (*write)(struct dw_hdmi *hdmi, u8 val, int offset);
>> + u8 (*read)(struct dw_hdmi *hdmi, int offset);
>> };
>>
>> +static void dw_hdmi_writel(struct dw_hdmi *hdmi, u8 val, int offset)
>> +{
>> + writel(val, hdmi->regs.p32 + offset);
> hdmi->regs + 4 * offset
>
>> +}
>> +
>> +static u8 dw_hdmi_readl(struct dw_hdmi *hdmi, int offset)
>> +{
>> + return readl(hdmi->regs.p32 + offset);
> same here
>
>> +}
>> +
>> +static void dw_hdmi_writeb(struct dw_hdmi *hdmi, u8 val, int offset)
>> +{
>> + writeb(val, hdmi->regs.p8 + offset);
>> +}
>> +
>> +static u8 dw_hdmi_readb(struct dw_hdmi *hdmi, int offset)
>> +{
>> + return readb(hdmi->regs.p8 + offset);
>> +}
>> +
>> static inline void hdmi_writeb(struct dw_hdmi *hdmi, u8 val, int offset)
>> {
>> - writeb(val, hdmi->regs + offset);
>> + hdmi->write(hdmi, val, offset);
>> }
>>
>> static inline u8 hdmi_readb(struct dw_hdmi *hdmi, int offset)
>> {
>> - return readb(hdmi->regs + offset);
>> + return hdmi->read(hdmi, offset);
>> }
>>
>> static void hdmi_modb(struct dw_hdmi *hdmi, u8 data, u8 mask, unsigned reg)
>> @@ -1508,6 +1536,7 @@ int dw_hdmi_bind(struct device *dev, struct device *master,
>> struct dw_hdmi *hdmi;
>> struct resource *iores;
>> int ret, irq;
>> + u32 val = 1;
>>
>> hdmi = devm_kzalloc(&pdev->dev, sizeof(*hdmi), GFP_KERNEL);
>> if (!hdmi)
>> @@ -1520,6 +1549,22 @@ int dw_hdmi_bind(struct device *dev, struct device *master,
>> hdmi->ratio = 100;
>> hdmi->encoder = encoder;
>>
>> + 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;
>> + }
>> +
>> ddc_node = of_parse_phandle(np, "ddc-i2c-bus", 0);
>> if (ddc_node) {
>> hdmi->ddc = of_find_i2c_adapter_by_node(ddc_node);
>> @@ -1544,9 +1589,9 @@ int dw_hdmi_bind(struct device *dev, struct device *master,
>> return ret;
>>
>> iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> - hdmi->regs = devm_ioremap_resource(dev, iores);
>> - if (IS_ERR(hdmi->regs))
>> - return PTR_ERR(hdmi->regs);
>> + hdmi->regs.p32 = devm_ioremap_resource(dev, iores);
>> + if (IS_ERR(hdmi->regs.p32))
>> + return PTR_ERR(hdmi->regs.p32);
>>
>> /* Product and revision IDs */
>> dev_info(dev,
> regards
> Philipp
>
>
>
>
--
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