From: CK Hu <ck.hu@mediatek.com>
To: <yongqiang.niu@mediatek.com>
Cc: Philipp Zabel <p.zabel@pengutronix.de>,
Rob Herring <robh+dt@kernel.org>,
Matthias Brugger <matthias.bgg@gmail.com>,
"David Airlie" <airlied@linux.ie>,
Daniel Vetter <daniel@ffwll.ch>,
Mark Rutland <mark.rutland@arm.com>,
<dri-devel@lists.freedesktop.org>, <devicetree@vger.kernel.org>,
<linux-kernel@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-mediatek@lists.infradead.org>
Subject: Re: [PATCH v1] drm/mediatek: fix up 1440x900 dp display black screen issue
Date: Wed, 27 Nov 2019 09:31:43 +0800 [thread overview]
Message-ID: <1574818303.15691.10.camel@mtksdaap41> (raw)
In-Reply-To: <1574750869-12611-1-git-send-email-yongqiang.niu@mediatek.com>
Hi, Yongqiang:
On Tue, 2019-11-26 at 14:47 +0800, yongqiang.niu@mediatek.com wrote:
> From: Yongqiang Niu <yongqiang.niu@mediatek.com>
>
> This patch fix up 1440x900 dp display black screen issue
> the computed result will overflow rdma1 fifo max size
> when external display pixel clock bigger than 74MHZ
>
> Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
> ---
> drivers/gpu/drm/mediatek/mtk_disp_rdma.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_disp_rdma.c b/drivers/gpu/drm/mediatek/mtk_disp_rdma.c
> index c1abde3..41143f5 100644
> --- a/drivers/gpu/drm/mediatek/mtk_disp_rdma.c
> +++ b/drivers/gpu/drm/mediatek/mtk_disp_rdma.c
> @@ -152,6 +152,10 @@ static void mtk_rdma_config(struct mtk_ddp_comp *comp, unsigned int width,
> * account for blanking, and with a pixel depth of 4 bytes:
> */
> threshold = width * height * vrefresh * 4 * 7 / 1000000;
> +
> + if (threshold > rdma_fifo_size)
> + threshold = rdma_fifo_size;
> +
This looks like that threshold is over spec. I think this FIFO is used
to cover the latency of reading data from DRAM. When data is read from
OVL not RDMA, OVL already has a FIFO, so RDMA FIFO is useless. So I
think you should set threshold to a special value when RDMA is in direct
link mode.
Regards,
CK
> reg = RDMA_FIFO_UNDERFLOW_EN |
> RDMA_FIFO_PSEUDO_SIZE(rdma_fifo_size) |
> RDMA_OUTPUT_VALID_FIFO_THRESHOLD(threshold);
prev parent reply other threads:[~2019-11-27 1:32 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-26 6:47 [PATCH v1] drm/mediatek: fix up 1440x900 dp display black screen issue yongqiang.niu
2019-11-27 1:31 ` CK Hu [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=1574818303.15691.10.camel@mtksdaap41 \
--to=ck.hu@mediatek.com \
--cc=airlied@linux.ie \
--cc=daniel@ffwll.ch \
--cc=devicetree@vger.kernel.org \
--cc=dri-devel@lists.freedesktop.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mediatek@lists.infradead.org \
--cc=mark.rutland@arm.com \
--cc=matthias.bgg@gmail.com \
--cc=p.zabel@pengutronix.de \
--cc=robh+dt@kernel.org \
--cc=yongqiang.niu@mediatek.com \
/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;
as well as URLs for NNTP newsgroup(s).