From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx009.vodafonemail.xion.oxcs.net ([153.92.174.39]) by bombadil.infradead.org with esmtps (Exim 4.89 #1 (Red Hat Linux)) id 1erlPB-0004VF-QK for barebox@lists.infradead.org; Fri, 02 Mar 2018 14:12:29 +0000 Date: Fri, 2 Mar 2018 15:11:06 +0100 (CET) From: Giorgio Dal Molin Message-ID: <272060361.5564.1519999866645@mail.vodafone.de> In-Reply-To: <20180302072606.nn5o4mj7zbe4pyna@pengutronix.de> References: <377910125.70611.1519914213534@mail.vodafone.de> <20180302072606.nn5o4mj7zbe4pyna@pengutronix.de> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: problems with am335x_sdram_size() To: Sascha Hauer Cc: barebox@lists.infradead.org Hi, > On March 2, 2018 at 8:26 AM Sascha Hauer wrote: > > > On Thu, Mar 01, 2018 at 03:23:33PM +0100, Giorgio Dal Molin wrote: > > Hi, > > > > working with the TI AM335x Evaluation Module I noticed that the function > > am335x_sdram_size() always returns 0 instead of the computed sdram size. > > > > I could trace back the problem to the fact that the function does its > > computation based on the value of the register CM_EMIF_SDRAM_CONFIG > > (addr. 0x44e10110), but this register is not written to by the function > > am33xx_config_sdram() and just returns its initial value (0). > > The datasheet says CM_EMIF_SDRAM_CONFIG should have the same value as > > AM33XX_EMIF4_0_REG(SDRAM_CONFIG) (addr. 0x4c000008) > > CM_EMIF_SDRAM_CONFIG is written when regs->zq_config is set and if it's > set then indeed the same value is written there as also written to > AM33XX_EMIF4_0_REG(SDRAM_CONFIG). > aaah, I'm blind ! I've added a line at the end of am33xx_config_sdram() that's exactly the same as the one a couple of lines before. I was so happy to have solved my problem that I've no more double checked if the register was already configured somewhere else. So, now I've also defined regs->zq_config in my lowlevel.c and everything works. The datasheet says: The CONTROL_EMIF_SDRAM_CONFIG register exports SDRAM configuration information to the EMIF after resuming from low power scenarios. This register should be loaded with the same value as SDRAM_CONFIG during DDR initialization. so I think we should initialize it unconditionally, not only if !regs->zq_config. Doing this it should be the same which one we use in am335x_sdram_size() to compute the sdram size even if I would prefer to use AM33XX_EMIF4_0_REG(SDRAM_CONFIG) for clarity. giorgio > > > > To conclude, to fix the problem with am335x_sdram_size() you can either > > use AM33XX_EMIF4_0_REG(SDRAM_CONFIG) instead of CM_EMIF_SDRAM_CONFIG > > in am335x_sdram_size(). > > > > or > > > > initialize CM_EMIF_SDRAM_CONFIG in am33xx_config_sdram() with the same value > > as AM33XX_EMIF4_0_REG(SDRAM_CONFIG) (regs->sdram_config) > > I'm fine with either way. Maybe the datasheet gives us a hint which way > to choose? Why is CM_EMIF_SDRAM_CONFIG only written when regs->zq_config > is set? Is this correct? > > 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 | > > _______________________________________________ > barebox mailing list > barebox@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/barebox _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox