Re: [PATCH v8 2/2] omap hsmmc: adaptation of sdma descriptor autoloading feature

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Chikkature Rajashekar, Madhusudhan had written, on 05/07/2010 11:59 AM, the following:


-----Original Message-----
From: Chikkature Rajashekar, Madhusudhan
Sent: Thursday, May 06, 2010 9:50 PM
To: Shilimkar, Santosh; 'kishore kadiyala'
Cc: S, Venkatraman; linux-omap@xxxxxxxxxxxxxxx; linux-
mmc@xxxxxxxxxxxxxxx; linux-arm-
kernel@xxxxxxxxxxxxxxxxxxxxxx; 'Adrian Hunter'; Kadiyala, Kishore; 'Tony
Lindgren'
Subject: RE: [PATCH v8 2/2] omap hsmmc: adaptation of sdma descriptor
autoloading feature


-----Original Message-----
From: Shilimkar, Santosh [mailto:santosh.shilimkar@xxxxxx]
Sent: Thursday, May 06, 2010 4:39 AM
To: kishore kadiyala
Cc: S, Venkatraman; linux-omap@xxxxxxxxxxxxxxx; linux-
mmc@xxxxxxxxxxxxxxx;
linux-arm-kernel@xxxxxxxxxxxxxxxxxxxxxx; Chikkature Rajashekar,
Madhusudhan; Adrian Hunter; Kadiyala, Kishore; Tony Lindgren
Subject: RE: [PATCH v8 2/2] omap hsmmc: adaptation of sdma descriptor
autoloading feature

-----Original Message-----
From: kishore kadiyala [mailto:kishorek.kadiyala@xxxxxxxxx]
Sent: Thursday, May 06, 2010 2:32 PM
To: Shilimkar, Santosh
Cc: S, Venkatraman; linux-omap@xxxxxxxxxxxxxxx; linux-
mmc@xxxxxxxxxxxxxxx; linux-arm-
kernel@xxxxxxxxxxxxxxxxxxxxxx; Chikkature Rajashekar, Madhusudhan;
Adrian Hunter; Kadiyala, Kishore;
Tony Lindgren
Subject: Re: [PATCH v8 2/2] omap hsmmc: adaptation of sdma
descriptor
autoloading feature
<<snip>>

I am not clear about the method. The board files export the
omap_mmc_platform_data.
Does it imply that all board files have to change and export
the capability so that it can be queried ?
No. You don't have to modify the board files. This would need
change in devices.c which common for all omap boards.

I don't have a strong opinion on this point but just put forth an
alternate way to avoid such SOC specific check in drivers.
You can take call on this
Agree. How about adding a flag in hsmmc.h & omap_mmc_platform_data,
that would take care of SDMA & SDMA_DLAOD in the driver instead
going
with SOC check .
Good idea Kishore.
Venkat,
Can you do what kishore is suggesting.

omap_mmc_platform_data is MMC specific platform data. Why add a SDMA
specific feature capability into it? Even though you add it there, you
will
still need to have a cpu check before that can be set in a common code.

CPU checks are allowed to be in the platform files. That is where such
machine/SOC specific differentiation should be done and not in the device
drivers.
That way device drivers remains clean and portable.

I want to stop this thread here since neither the patch author nor the
file
maintainer thinks that cpu checks in the device drivers is bad idea.

Please decide within yourself and move on.


I am not saying that it is wrong. My point here is that adding this
particular flag into MMC platform data to differentiate a SDMA specific
feature which got introduced post certain SOC may not be needed. But you can
always post your comments on the list which will be looked at by a wider
audience and finally the right patch will go in.
Please see [1] for SOC specific feature handling. any reasons we can't handle it by adding a new feature?

[1] http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=arch/arm/plat-omap/include/plat/cpu.h#l439

--
Regards,
Nishanth Menon
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