From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Subject: Re: [PATCH] Do set var even if no fb_check_var() provided. Date: Wed, 27 Aug 2008 09:08:09 +0200 (CEST) Message-ID: References: <48B4E16C.4000107@renesas.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1KYF8c-0003RC-5T for linux-fbdev-devel@lists.sourceforge.net; Wed, 27 Aug 2008 00:08:18 -0700 Received: from nelson.telenet-ops.be ([195.130.133.66]) by mail.sourceforge.net with esmtp (Exim 4.44) id 1KYF8a-0008Sz-Gh for linux-fbdev-devel@lists.sourceforge.net; Wed, 27 Aug 2008 00:08:18 -0700 In-Reply-To: <48B4E16C.4000107@renesas.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-fbdev-devel-bounces@lists.sourceforge.net Errors-To: linux-fbdev-devel-bounces@lists.sourceforge.net To: Takashi Yoshii Cc: linux-fbdev-devel@lists.sourceforge.net On Wed, 27 Aug 2008, Takashi Yoshii wrote: > The behavior of FBIOSET_VSCREENINFO seems to be weired on FB which does not > provides fbops->fb_check_var. > It doesn't set anything, but gets info->var instead, and returns no error. > It is just same as FBIOGET_VSCREENINFO does. > > IMHO, this should be one of the following candidates, > 1. set var without check. > 2. do nothing but return error (setting var is not supported). > or > 3. it's a bug (fb_check_var should always be provided). > > The patch at the bottom implements "1". > > Because I don't know API specification, nor the history of the code, > I would like people who knows well to discuss this. If the driver doesn't provide a fb_check_var(), it means it cannot change video mode. Hence this rules out #1. #2 is not acceptable, as it will break existing applications. It's also incorrect, as FBIOPUT_VSCREENINFO should succeed for supported modes. For unsupported modes, the mode should be rounded up to a supported mode, if possible. In the case of drivers that support one fixed mode only, this rounding up is relaxed to `rounding' to the sole supported mode. #3 is also wrong, as fb_check_var() has been deliberately made optional to simplify drivers that support one fixed mode only. Conclusion: nothing should be changed? Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/