From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Lechner Date: Thu, 15 Mar 2018 09:32:47 -0500 Subject: [U-Boot] [PATCH] davinci: omapl138_lcdk: fix PLL0 frequency In-Reply-To: <25797151-dd92-411e-7d20-c2af0c16a294@ti.com> References: <1521077790-17411-1-git-send-email-david@lechnology.com> <25797151-dd92-411e-7d20-c2af0c16a294@ti.com> Message-ID: <1ec2acb6-15c0-90e5-ade5-e45fbbaafb62@lechnology.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 03/15/2018 07:34 AM, Sekhar Nori wrote: > Hi David, > > On Thursday 15 March 2018 07:06 AM, David Lechner wrote: >> commit 1601dd97edc6 ("davinci: omapl138_lcdk: increase PLL0 frequency") >> changed the PLL0 frequency to 456MHz, which is needed for the LCDC IP >> block. However, in doing so, it caused the PLLOUT clock to be outside >> of the allowable specifications given in the OMAP-L138 data sheet. (It >> says PLLOUT must be 600MHz max). It also uses a PLLM value outside of >> the range given in the TRM (it says PLLM must in the range 0 to 0x1f). >> >> So here is what we have currently: >> >> PLLOUT = 24 / (0 + 1) * (37 + 1) = 912MHz (out of spec) >> ^ ^ ^ >> CLKIN PREDIV PLLM (out of spec) >> >> input to PLLDIVn = 912 / (1 + 1) = 456MHz (desired result) >> ^ ^ >> PLLOUT POSTDIV >> >> This changes the PLLM value to 18 and the POSTDIV value to 0 so that >> PLLOUT is now within specification but we still get the desired >> result. >> >> PLLOUT = 24 / (0 + 1) * (18 + 1) = 456MHz (within spec) >> ^ ^ ^ >> CLKIN PREDIV PLLM >> >> input to PLLDIVn = 456 / (0 + 1) = 456MHz (desired result) >> ^ ^ >> PLLOUT POSTDIV >> >> Fixes: 1601dd97edc6 ("davinci: omapl138_lcdk: increase PLL0 frequency") >> Signed-off-by: David Lechner > > Thanks for the patch and great description. It looks correct to me. > Hopefully I can provide some testing feedback too soon. > >> --- >> >> FYI, I haven't been able to test this patch yet. The changes affect the SPL >> image, which has to be flashed to SPI. I am having trouble with the flash >> utility[1] running on Linux. It gets stuck at: >> >> 0% [ ------------------------------------------------------------ ] >> Programming application into flash... >> >> So, if anyone has some advice on how to make it work or can test the patch, >> that would be helpful. > > The easiest thing to do would be to shift to MMC/SD boot so you can > easily update images. > > Before starting though, I would take note of out-of-the-box boot switch > settings and also take a disk image backup of the SD card. Or better > yet, just use another SD card. > > Setup the SW1 dip switch thus: > http://processors.wiki.ti.com/index.php/How_to_boot_OMAP-L138_LCDK_from_SD_card#Settings_DIP_switches_to_SD.2FMMC_boot_mode > > Prepare an SD card for boot: > > $ sudo dd if=u-boot.ais of=/dev/sd seek=117 bs=512 conv=fsync Thanks for the tips. I've actually done exactly that (using my own SD card). However, these changes affect the u-boot SPL image only. I was able to put the regular u-boot.ais on the SD card, but I'm having troubling figuring out how to install the SPL image.