linux-kernel - Re: [PATCH v11 05/10] drm/mediatek: Add MT8195 Embedded DisplayPort driver

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 21 Jun 2022 20:21:22 +0800
From:   Rex-BC Chen <rex-bc.chen@...iatek.com>
To:     CK Hu <ck.hu@...iatek.com>,
        "chunkuang.hu@...nel.org" <chunkuang.hu@...nel.org>,
        "p.zabel@...gutronix.de" <p.zabel@...gutronix.de>,
        "daniel@...ll.ch" <daniel@...ll.ch>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "krzysztof.kozlowski+dt@...aro.org" 
        <krzysztof.kozlowski+dt@...aro.org>,
        "mripard@...nel.org" <mripard@...nel.org>,
        "tzimmermann@...e.de" <tzimmermann@...e.de>,
        "matthias.bgg@...il.com" <matthias.bgg@...il.com>,
        "deller@....de" <deller@....de>,
        "airlied@...ux.ie" <airlied@...ux.ie>
CC:     "msp@...libre.com" <msp@...libre.com>,
        "granquet@...libre.com" <granquet@...libre.com>,
        Jitao Shi (石记涛) 
        <jitao.shi@...iatek.com>,
        "wenst@...omium.org" <wenst@...omium.org>,
        "angelogioacchino.delregno@...labora.com" 
        <angelogioacchino.delregno@...labora.com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-mediatek@...ts.infradead.org" 
        <linux-mediatek@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
        Project_Global_Chrome_Upstream_Group 
        <Project_Global_Chrome_Upstream_Group@...iatek.com>
Subject: Re: [PATCH v11 05/10] drm/mediatek: Add MT8195 Embedded DisplayPort
 driver

On Mon, 2022-06-20 at 11:19 +0800, CK Hu wrote:
> On Mon, 2022-06-20 at 11:12 +0800, CK Hu wrote:
> > On Fri, 2022-06-10 at 18:55 +0800, Bo-Chen Chen wrote:
> > > From: Markus Schneider-Pargmann <msp@...libre.com>
> > > 
> > > This patch adds a embedded displayport driver for the MediaTek
> > > mt8195
> > > SoC.
> > > 
> > > It supports the MT8195, the embedded DisplayPort units. It offers
> > > DisplayPort 1.4 with up to 4 lanes.
> > > 
> > > The driver creates a child device for the phy. The child device
> > > will
> > > never exist without the parent being active. As they are sharing
> > > a
> > > register range, the parent passes a regmap pointer to the child
> > > so
> > > that
> > > both can work with the same register range. The phy driver sets
> > > device
> > > data that is read by the parent to get the phy device that can be
> > > used
> > > to control the phy properties.
> > > 
> > > This driver is based on an initial version by
> > > Jitao shi <jitao.shi@...iatek.com>
> > > 
> > > Signed-off-by: Markus Schneider-Pargmann <msp@...libre.com>
> > > Signed-off-by: Guillaume Ranquet <granquet@...libre.com>
> > > [Bo-Chen: Cleanup the drivers and modify comments from reviewers]
> > > Signed-off-by: Bo-Chen Chen <rex-bc.chen@...iatek.com>
> > > ---
> > 
> > [snip]
> > 
> > > +
> > > +static void mtk_dp_calculate_pixrate(struct mtk_dp *mtk_dp)
> > > +{
> > > +	u8 target_frame_rate = 60;
> > > +	u32 target_pixel_clk;
> > > +	struct drm_display_mode mode;
> > > +	struct mtk_dp_timings *timings = &mtk_dp->info.timings;
> > > +
> > > +	drm_display_mode_from_videomode(&timings->vm, &mode);
> > > +
> > > +	if (mtk_dp->info.timings.frame_rate > 0) {
> > > +		target_frame_rate = mtk_dp->info.timings.frame_rate;
> > > +		target_pixel_clk = mode.htotal * mode.vtotal *
> > > +				   target_frame_rate;
> > > +	} else if (mtk_dp->info.timings.pix_rate_khz > 0) {
> > > +		target_pixel_clk = mtk_dp->info.timings.pix_rate_khz *
> > > 1000;
> > > +	} else {
> > > +		target_pixel_clk = mode.htotal * mode.vtotal *
> > > +				   target_frame_rate;
> > > +	}
> > > +
> > > +	mtk_dp->info.timings.pix_rate_khz = target_pixel_clk / 1000;
> > 
> > It seems that pix_rate_khz is used only here and does not used in
> > another place, so pix_rate_khz is useless, remove it.
> 
> It seems that frame_rate is also redundant, so remove it.
> 
> Regards,
> CK
> 

I think we do use this variable in mtk_dp_parse_drm_mode_timings()
We use this variable to get target framerate.

BRs,
Bo-Chen

> > 
> > Regards,
> > CK
> > 
> > > +}
> > > +
> 
>