linux-kernel - Re: [RFC PATCH] video: Use fb_sys_write rather than open-coding in drivers

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Message-ID: <52FB2DFD.8080408@ti.com>
Date:	Wed, 12 Feb 2014 10:17:01 +0200
From:	Tomi Valkeinen <tomi.valkeinen@...com>
To:	Ryan Mallon <rmallon@...il.com>
CC:	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>,
	"linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] video: Use fb_sys_write rather than open-coding in
 drivers

On 12/02/14 07:02, Ryan Mallon wrote:

> Well, the alternative is to supply an fb_write() implementation for each
> driver that calls fb_sys_write(), and then updates the display. The
> fb_sync() additions can be removed. That would cut down the boiler-plate
> code, and should keep the behaviour the same.
> 
> If you don't think it is worth the effort, then the patch can just be
> dropped.

I'd be very cautious about doing cleanups on drivers that you cannot
test. Small innocent looking changes can break them.

For example, your patch sets info->screen_size, which is not set
currently. Does the fbdev framework use screen_size somewhere
differently than smem_len? I don't know, but that could lead to small
difference in operation. However, in this case, fb_sys_write() actually
uses smem_len if screen_size is 0, so that change is not even needed.

ssd1307fb_write() looks a bit different than fb_sys_write. I don't know
if the differences could cause issues. The other ones look copy-pasted
from fb_sys_write (but I didn't look at them carefully), so perhaps
those could be cleaned up safely.

 Tomi

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