Re: [PATCH v3 13/13] scsi: ufs: Add exynos ufs platform data

From: Alim Akhtar <alim.akhtar@gmail.com>
To: Rob Herring <robh@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Yaniv Gardi <ygardi@codeaurora.org>,
	Alim Akhtar <alim.akhtar@samsung.com>,
	kbuild test robot <lkp@intel.com>,
	kbuild-all@01.org, linux-scsi@vger.kernel.org,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"James E.J. Bottomley" <JBottomley@odin.com>,
	vinayak holikatti <vinholikatti@gmail.com>,
	Amit Kachhap <amit.daniel@samsung.com>,
	Seungwon Jeon <essuuj@gmail.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
Subject: Re: [PATCH v3 13/13] scsi: ufs: Add exynos ufs platform data
Date: Mon, 5 Oct 2015 20:50:10 +0530	[thread overview]
Message-ID: <CAGOxZ51BKfh_FyJ9pWv56a0QXUE4Kd3oZM7Ruu6ACg6GsQwyXQ@mail.gmail.com> (raw)
In-Reply-To: <CAL_JsqJWzqMkkMH8myFX1eeuV-U25Ri_nWhjj2mb3AWh5tzDZA@mail.gmail.com>

Hi Rob,

On Mon, Oct 5, 2015 at 7:41 PM, Rob Herring <robh@kernel.org> wrote:
> On Mon, Oct 5, 2015 at 4:06 AM, Arnd Bergmann <arnd@arndb.de> wrote:
>> On Monday 05 October 2015 13:44:29 Alim Akhtar wrote:
>>> CCing Rob Herring,
>>>
>>> Hi Arnd,
>>>
>>> On 10/01/2015 04:59 PM, Arnd Bergmann wrote:
>>> > On Thursday 01 October 2015 18:46:34 kbuild test robot wrote:
>>> >> [auto build test results on v4.3-rc3 -- if it's inappropriate base, please ignore]
>>> >>
>>> >> config: x86_64-allmodconfig (attached as .config)
>>> >> reproduce:
>>> >>          git checkout 6e153e3bf7c68b019e987c5a0ffadebd9c7d4fbb
>>> >>          # save the attached .config to linux build tree
>>> >>          make ARCH=x86_64
>>> >>
>>> >> All error/warnings (new ones prefixed by >>):
>>> >>
>>> >>>> ERROR: "ufs_hba_exynos_ops" [drivers/scsi/ufs/ufshcd-pltfrm.ko] undefined!
>>> >>
>>> >>
>>> >
>>> > Ah, this seems to be a case of layering violation. It would be best to
>>> > restructure the code so that the exynos driver registers a platform_driver
>>> > by itself for the respective DT compatible string, and then calls
>>> > into the common code from its probe function, rather than having the
>>> > generic driver know about the specific backends.
>>> >
>>> > That approach will also make the generic driver more scalable as we
>>> > add further chip-specific variations, and matches what we do in other
>>> > drivers.
>>> >
>>>
>>> Looks like some discussions on ufs variant driver probe method happened
>>> here [1] few months back.
>>> [1]-> https://lkml.org/lkml/2015/6/3/180
>>
>> Hmm, too bad we didn't catch it then, it's much more work to fix now.
>
> What you suggested is what is being implemented[1]. It is not merged
> yet. The core is a library and the platform specific parts create the
> driver.
>
> Rob
>
> [1] https://lkml.org/lkml/2015/9/2/364

Thanks for the pointer...let me have a look. At least now we have
another variant to test it out.

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-- 
Regards,
Alim