From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sascha Hauer Date: Fri, 26 Jul 2013 07:38:48 +0000 Subject: Re: [PATCH 2/2] video: imxfb: Add feature to setup PWM Contrast Control Register Message-Id: <20130726073848.GF2737@pengutronix.de> List-Id: References: <1374395709-20898-1-git-send-email-shc_work@mail.ru> <1374395709-20898-2-git-send-email-shc_work@mail.ru> <20130725133824.GD16871@s25.your-server.de> <20130725212053.b39198a8610efc157a91b7be@mail.ru> In-Reply-To: <20130725212053.b39198a8610efc157a91b7be@mail.ru> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arm-kernel@lists.infradead.org On Thu, Jul 25, 2013 at 09:20:53PM +0400, Alexander Shiyan wrote: > On Thu, 25 Jul 2013 15:38:56 +0200 > Markus Pargmann wrote: > > > Hi, > > > > On Sun, Jul 21, 2013 at 12:35:09PM +0400, Alexander Shiyan wrote: > > > This patch adds feature to setup PWM Contrast Control Register. > > > This register is used to control the signal output at the contrast pin, > > > which controls contrast of the LCD panel. > > > > http://www.spinics.net/lists/linux-fbdev/msg10002.html > > PWM? I can not understand how the PWM driver will be connected to the > framebuffer driver. It is not backlight, this is contrast. > Even if we imagine that the driver will be connected through phandle, > then we will need to have at least 4! additional parameters in the framebuffer > driver: freq source, frequency and active pulse period + phandle to PWM. > Is it worth it, given that these parameters should not be adjustable? > On my opinion, the only one additional parameter in framebuffer is enough. > Thanks. Why should the contrast of a display not be adjustable? Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | From mboxrd@z Thu Jan 1 00:00:00 1970 From: s.hauer@pengutronix.de (Sascha Hauer) Date: Fri, 26 Jul 2013 09:38:48 +0200 Subject: [PATCH 2/2] video: imxfb: Add feature to setup PWM Contrast Control Register In-Reply-To: <20130725212053.b39198a8610efc157a91b7be@mail.ru> References: <1374395709-20898-1-git-send-email-shc_work@mail.ru> <1374395709-20898-2-git-send-email-shc_work@mail.ru> <20130725133824.GD16871@s25.your-server.de> <20130725212053.b39198a8610efc157a91b7be@mail.ru> Message-ID: <20130726073848.GF2737@pengutronix.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Jul 25, 2013 at 09:20:53PM +0400, Alexander Shiyan wrote: > On Thu, 25 Jul 2013 15:38:56 +0200 > Markus Pargmann wrote: > > > Hi, > > > > On Sun, Jul 21, 2013 at 12:35:09PM +0400, Alexander Shiyan wrote: > > > This patch adds feature to setup PWM Contrast Control Register. > > > This register is used to control the signal output at the contrast pin, > > > which controls contrast of the LCD panel. > > > > http://www.spinics.net/lists/linux-fbdev/msg10002.html > > PWM? I can not understand how the PWM driver will be connected to the > framebuffer driver. It is not backlight, this is contrast. > Even if we imagine that the driver will be connected through phandle, > then we will need to have at least 4! additional parameters in the framebuffer > driver: freq source, frequency and active pulse period + phandle to PWM. > Is it worth it, given that these parameters should not be adjustable? > On my opinion, the only one additional parameter in framebuffer is enough. > Thanks. Why should the contrast of a display not be adjustable? Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |