Re: [PATCH V5 2/2] mfd: stmpe: Update DT support in stmpe driver

From: Viresh Kumar <viresh.kumar@linaro.org>
To: Lee Jones <lee.jones@linaro.org>
Cc: Grant Likely <grant.likely@secretlab.ca>,
	Samuel Ortiz <sameo@linux.intel.com>,
	rabin.vincent@stericsson.com, shiraz.hashim@st.com,
	devicetree-discuss@lists.ozlabs.org,
	linux-kernel@vger.kernel.org, spear-devel@list.st.com,
	linus.walleij@linaro.org,
	Vipul Kumar Samar <vipulkumar.samar@st.com>
Subject: Re: [PATCH V5 2/2] mfd: stmpe: Update DT support in stmpe driver
Date: Thu, 6 Dec 2012 15:49:27 +0530	[thread overview]
Message-ID: <CAKohpom9NK0Tg9fKdddkP-0H8FuVd-=yhHzZr-sWNb_zTVymWw@mail.gmail.com> (raw)
In-Reply-To: <20121206101131.GP2718@gmail.com>

On 6 December 2012 15:41, Lee Jones <lee.jones@linaro.org> wrote:
> So then I'm back to my original question, why?
>
> What is it used for? What difference does it make?
>
> I could understand if the .data attribute was used in the driver
> to make vital decisions based on STMPE version, but it's not. So
> why are we burdening the driver with unused code that's not
> required? Other than to get your mainlined patch-count up of
> course? This has an air of "placing header files in alphabetical
> order" about it. ;)

The count would still be the same as some part of this patch will
go :)

I said that because of Grant's comment: "An of_match_table is the
robust way of identifying specific devices and allows for matching
against any entry in the compatible list."

So, thought its better we keep it.

Now, the problem is, with this new table we will bind device and
driver based on of_device_id table and probe it using device_id
table. Ahh.. that's broken. Maybe yes, can remove it unless we
have a real need of it.

>> By chance
>> our non-DT and DT tables had a difference of "st," only in the name
>> of instances and so it worked without tables. Otherwise it couldn't
>> have worked.
>>
>> Over that, i am looking to bring the "stmpe,id" binding back again (unless
>> you have a better option), as device name is not coming from DT currently,
>> which we discussed earlier.
>
> Or you could not put unnecessary bindings into the Device Tree
> by putting two and two together and realise that using the table
> is the correct thing to do instead. This actually gives reason
> to you previous patch, but should probably be fixed-up into it
> so it has some proper meaning/purpose. ;)

Couldn't understand this one :(