From: Sascha Hauer <s.hauer@pengutronix.de>
To: Daniel Schultz <d.schultz@phytec.de>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH] arm: am33xx: Initialize EMIF REG_PR_OLD_COUNT
Date: Mon, 30 Jan 2017 07:26:50 +0100 [thread overview]
Message-ID: <20170130062650.2cxt43bcowmztnr7@pengutronix.de> (raw)
In-Reply-To: <1485419144-41804-1-git-send-email-d.schultz@phytec.de>
On Thu, Jan 26, 2017 at 09:25:44AM +0100, Daniel Schultz wrote:
> This patch is based on a patch from the U-Boot and fixes two errors with
> the LCDC. Original commit message from Jyri Sarha [1]:
> "Initialize EMIF OCP_CONFIG registers REG_COS_COUNT_1, REG_COS_COUNT_2,
> and REG_PR_OLD_COUNT field for Beaglebone-Black and am335x-evm. With
> the default values LCDC suffers from DMA FIFO underflows and frame
> synchronization lost errors. The initialization values are the highest
> that work flawlessly when heavy memory load is generated by CPU. 32bpp
> colors were used in the test. On BBB the video mode used 110MHz pixel
> clock. The mode supported by the panel of am335x-evm uses 30MHz pixel
> clock."
>
> The register values are generated by testing, because there is no formula
> to calculate them. Also from Jyri Sarha [1]:
> "In practice the only rule to find an optimal value is to find as high as
> possible REG_PR_OLD_COUNT value that does not produce LCDC FIFO
> underflows under worst case scenario. The worst case happens when the
> highest pixel clock videomode with maximum bpp is used while memory
> subsystem is stressed by endless stream of writes hitting the same
> memory memory bank (can be the same address)."
>
> It only contains the BeagleBone Black and the Phytec SoM, because I
> don't have other boards.
>
> [1] https://patchwork.ozlabs.org/patch/704013/
>
> Signed-off-by: Daniel Schultz <d.schultz@phytec.de>
Applied, thanks. Nice fix, I think I have been searching for this for a
while some time ago without success.
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
prev parent reply other threads:[~2017-01-30 6:29 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-26 8:25 Daniel Schultz
2017-01-30 6:26 ` Sascha Hauer [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170130062650.2cxt43bcowmztnr7@pengutronix.de \
--to=s.hauer@pengutronix.de \
--cc=barebox@lists.infradead.org \
--cc=d.schultz@phytec.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox