McBSP register question

McBSP register question

[Jason Marini]

Looking at the latest git head, I see that omap_mcbsp_pollwrite() and
omap_mcbsp_pollread() improperly use readw() and writew() instead of
OMAP_MCBSP_READ() and OMAP_MCBSP_WRITE() in the file
arch/arm/plat-omap/mcbsp.c.

But while I was editing this file, I also saw writes to
OMAP_MCBSP_REG_DXR1, which is #define'd for ARCH_OMAP_34XX and
ARCH_OMAP_24XX to be at an offset of 0x0C.  The McBSP section of the
TRM for the OMAP34xx has no mention of any registers existing at this
offset.

Why is this DXR1 and not just DXR?

-Jason Marini
Associate Software Engineer
Vocollect, Inc.

Re: McBSP register question

[shekhar, chandra]

----- Original Message ----- 
From: "Jason Marini" <jason.marini@gmail.com>
To: <linux-omap@vger.kernel.org>
Sent: Friday, December 12, 2008 11:51 PM
Subject: McBSP register question


> Looking at the latest git head, I see that omap_mcbsp_pollwrite() and
> omap_mcbsp_pollread() improperly use readw() and writew() instead of
> OMAP_MCBSP_READ() and OMAP_MCBSP_WRITE() in the file
> arch/arm/plat-omap/mcbsp.c.
>
> But while I was editing this file, I also saw writes to
> OMAP_MCBSP_REG_DXR1, which is #define'd for ARCH_OMAP_34XX and
> ARCH_OMAP_24XX to be at an offset of 0x0C.  The McBSP section of the
> TRM for the OMAP34xx has no mention of any registers existing at this
> offset.
>
> Why is this DXR1 and not just DXR?

It so happens that McBSP on 2420 has DXR1 and DXR2 registers, but not on 
omap2430/34xx.
To provide multi-omap suport and avoid ifdefs dxr1/2 and drr1/2 has been 
retained along with dxr and drr  (same code mach-omap2/mcbsp.c supports 2420.) .



>
> -Jason Marini
> Associate Software Engineer
> Vocollect, Inc.
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Re: McBSP register question

[Jason Marini]

On Sun, Dec 14, 2008 at 9:38 PM, shekhar, chandra <x0044955@ti.com> wrote:
> ----- Original Message ----- From: "Jason Marini" <jason.marini@gmail.com>
> To: <linux-omap@vger.kernel.org>
> Sent: Friday, December 12, 2008 11:51 PM
> Subject: McBSP register question
>
>
>> Looking at the latest git head, I see that omap_mcbsp_pollwrite() and
>> omap_mcbsp_pollread() improperly use readw() and writew() instead of
>> OMAP_MCBSP_READ() and OMAP_MCBSP_WRITE() in the file
>> arch/arm/plat-omap/mcbsp.c.
>>
>> But while I was editing this file, I also saw writes to
>> OMAP_MCBSP_REG_DXR1, which is #define'd for ARCH_OMAP_34XX and
>> ARCH_OMAP_24XX to be at an offset of 0x0C.  The McBSP section of the
>> TRM for the OMAP34xx has no mention of any registers existing at this
>> offset.
>>
>> Why is this DXR1 and not just DXR?
>
> It so happens that McBSP on 2420 has DXR1 and DXR2 registers, but not on
> omap2430/34xx.
> To provide multi-omap suport and avoid ifdefs dxr1/2 and drr1/2 has been
> retained along with dxr and drr  (same code mach-omap2/mcbsp.c supports
> 2420.) .

I suspected as much - thank you for the response.

-Jason