linux-kernel - Re: [PATCH V2 1/2] imx-drm: imx-hdmi: split imx soc specific code from imx-hdmi

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Message-ID: <545C34F1.5020206@rock-chips.com>
Date:	Fri, 07 Nov 2014 10:56:49 +0800
From:	Andy Yan <andy.yan@...k-chips.com>
To:	Zubair Lutfullah Kakakhel <Zubair.Kakakhel@...tec.com>,
	airlied@...ux.ie, heiko@...ech.de, fabio.estevam@...escale.com,
	rmk+kernel@....linux.org.uk
CC:	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>,
	Lucas Stach <l.stach@...gutronix.de>, 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
Subject: Re: [PATCH V2 1/2] imx-drm: imx-hdmi: split imx soc specific code
 from imx-hdmi


On 2014年11月05日 21:30, Zubair Lutfullah Kakakhel wrote:
> This one patch does too much to be reviewed easily.
>
> One patch is supposed to modify/add one thing at a time in the kernel.
>
> Separating platform specific code from imx-drm/imx-hdmi is one thing.
>
> Adding support for multi-byte register access is something different.
>
> i.e. Something like.
> 1/3 split platform specific code out.
> 2/3 move/rename imx-hdmi outside the folder
> 3/3 add support for multi byte register width access.
>
> If there are other things that are not directly relevant to the patch,
> it goes in a different patch. Bug fixes are also separate.
>
> This should result in readable patches that can be reviewed easily.
I have split the patch in three parts in PATCH V3, tkanks for your 
suggestion
>
> Also, the approach with 4 byte access is ok. But you could use reg-shifts as well perhaps.
> Then you won't have to change so much of the code.
>
> static inline void hdmi_writeb(struct dwc_hdmi *hdmi, u8 val, int offset)
> +{
> + writeb(val, hdmi->regs + (offset << hdmi->reg_shift));
> +}
> +
> +static inline u8 hdmi_readb(struct dwc_hdmi *hdmi, int offset)
> +{
> + return readb(hdmi->regs + (offset << hdmi->reg_shift));
> +}
>
> And then in probe
>
> +hdmi->reg_shift = 0;
> +
> + if (of_property_read_u32(np, "reg-shift", &hdmi->reg_shift))
> + dev_warn(hdmi->dev, "No reg-shift\n");
>
> This way the reg-shift property can be defined using DT

rk3288 can only access the register by 32bits(readl/writel), byte access 
will causes an
imprecise external abort.
I have refactor the register access in PATCH V3, if you have any futher 
suggestion ,please
tell me.

>
> Cheers,
> ZubairLK
>
> On 05/11/14 12:59, Andy Yan wrote:
>> imx6 and rockchip rk3288 and JZ4780 (Ingenic Xburst/MIPS)
>> use the interface compatible Designware HDMI IP, but they
>> also have some lightly difference, such as phy pll configuration,
>> register width(imx hdmi register is one byte, but rk3288 is 4
>> bytes width), 4K support(imx6 doesn't support 4k, but rk3288 does),
>> clk useage,and the crtc mux configuration is also platform specific.
>>
>> To reuse the imx hdmi driver, split the platform specific code out
>> to dw_hdmi-imx.c.
>>
>> Signed-off-by: Andy Yan <andy.yan@...k-chips.com>
>> ---
>>   drivers/staging/imx-drm/Makefile      |   2 +-
>>   drivers/staging/imx-drm/dw_hdmi-imx.c | 214 ++++++++++
>>   drivers/staging/imx-drm/imx-hdmi.c    | 726 ++++++++++++++--------------------
>>   include/drm/bridge/dw_hdmi.h          | 114 ++++++
>>   4 files changed, 634 insertions(+), 422 deletions(-)
>>   create mode 100644 drivers/staging/imx-drm/dw_hdmi-imx.c
>>   create mode 100644 include/drm/bridge/dw_hdmi.h
>
>


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