From mboxrd@z Thu Jan 1 00:00:00 1970 From: Archit Taneja Subject: Re: [PATCH] clk: qcom: Fix pre-divider usage for pixel RCG Date: Sun, 28 Feb 2016 15:36:12 +0530 Message-ID: <56D2C694.5060808@codeaurora.org> References: <1456464655-3684-1-git-send-email-architt@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:54132 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751477AbcB1KGT (ORCPT ); Sun, 28 Feb 2016 05:06:19 -0500 In-Reply-To: Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: John Stultz Cc: Stephen Boyd , "linux-arm-msm@vger.kernel.org" , Vinay Simha On 2/27/2016 2:10 AM, John Stultz wrote: > On Thu, Feb 25, 2016 at 9:30 PM, Archit Taneja wrote: >> The clk_rcg_pixel_set_rate clk_op sets up the pre-divider by reading >> its current value from the NS register. >> >> Using the pre-divider wasn't really intended when creating these ops. >> The pixel RCG was only intended to achieve fractional multiplication >> provided in the pixel_table array. Leaving the pre-divider to the >> existing register value results in a wrong pixel clock when the >> bootloader sets up the display. This was left unidentified because >> the IFC6410 Plus board on which this was verified didn't have a >> bootloader that configured the display. >> >> Don't set the RCG pre-divider in freq_tbl to the existing NS register >> value. Instead, set it based on the fractional multiplication we want. >> Prevent using M/N counter when we can just manage with using the >> pre-divider. >> >> Cc: John Stultz >> Cc: Vinay Simha >> Signed-off-by: Archit Taneja >> --- >> John, Vinay, could you please test this on N7 and confirm if it works? > > Hey Archit, > > So this did not work for me. I removed the earlier patch forcing > pre_div to 1, and added this, but that ended up with a mostly black > screen with a bit of blue slowly scrolling down the side. > > With the f.pre_div=1 line re-added, I don't see anything. The screen > just goes black and doesn't come back. > > Let me know if I can test anything else for you, or add any debug messages. Thanks for trying the patch. There was a small optimization which seems to make things worse for us. I'm going to post out a v2 which does the same thing as the earlier patch. Archit > > thanks > -john > -- > To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project