From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nishanth Menon Subject: Re: [PATCH v8 2/2] omap hsmmc: adaptation of sdma descriptor autoloading feature Date: Sun, 09 May 2010 11:06:37 -0500 Message-ID: <4BE6DD8D.6030201@gmail.com> References: <004501caed38$03e7b9f0$544ff780@am.dhcp.ti.com> <000601caee06$b2c8a9b0$544ff780@am.dhcp.ti.com> <4BE4694F.3060901@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-mmc-owner@vger.kernel.org To: Venkatraman S Cc: Nishanth Menon , "Chikkature Rajashekar, Madhusudhan" , "Shilimkar, Santosh" , kishore kadiyala , "linux-omap@vger.kernel.org" , "linux-mmc@vger.kernel.org" , "linux-arm-kernel@lists.arm.linux.org.uk" , Adrian Hunter , "Kadiyala, Kishore" , Tony Lindgren List-Id: linux-omap@vger.kernel.org On 05/09/2010 05:51 AM, Venkatraman S wrote: > Nishanth Menon wrote: >> 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@vger.kernel.org; linux- >>>> >>>> mmc@vger.kernel.org; linux-arm- >>>>> >>>>> kernel@lists.arm.linux.org.uk; '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@ti.com] >>>>>> Sent: Thursday, May 06, 2010 4:39 AM >>>>>> To: kishore kadiyala >>>>>> Cc: S, Venkatraman; linux-omap@vger.kernel.org; linux- >>>> >>>> mmc@vger.kernel.org; >>>>>> >>>>>> linux-arm-kernel@lists.arm.linux.org.uk; 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@gmail.com] >>>>>>> Sent: Thursday, May 06, 2010 2:32 PM >>>>>>> To: Shilimkar, Santosh >>>>>>> Cc: S, Venkatraman; linux-omap@vger.kernel.org; linux- >>>>>> >>>>>> mmc@vger.kernel.org; linux-arm- >>>>>>> >>>>>>> kernel@lists.arm.linux.org.uk; Chikkature Rajashekar, Madhusudhan; >>>>>> >>>>>> Adrian Hunter; Kadiyala, Kishore; >>>>>>> >>>>>>> Tony Lindgren >>>>>>> Subject: Re: [PATCH v8 2/2] omap hsmmc: adaptation of sdma >>>> >>>> descriptor >>>>>> >>>>>> autoloading feature >>>>>>> >>>>>>> <> >>>>>>> >>>>>>>>> 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 >> > > Thanks. I can add a new feature here, but I see that the API is tied > to OMAP3, whereas the DMA feature is common > to 3630, OMAP4 and mostly everything after that. I can work on an > upgrade, but do you see that > as a dependency and done on the context of this patch ? > Regards, > Venkat. Yes, I am aware that the current APIs are tied to OMAP3, no reason that we cant introduce a OMAP version independent feature.. Yes, IMHO, this is an SOC specific feature that has no place in a platform data.. lets not misuse that. Regards, NM