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]

Message-ID: <127049c096eea15b9dad37ce1b6e4be810c24a93.camel@mediatek.com>
Date:   Fri, 17 Jun 2022 16:27:43 +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 Wed, 2022-06-15 at 11:06 +0800, CK Hu wrote:
> Hi, Bo-Chen:
> 
> 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 int mtk_dp_parse_capabilities(struct mtk_dp *mtk_dp)
> > +{
> > +	u8 val;
> > +	struct mtk_dp_train_info *train_info = &mtk_dp->train_info;
> > +
> > +	drm_dp_dpcd_writeb(&mtk_dp->aux, DP_SET_POWER,
> > DP_SET_POWER_D0);
> > +	usleep_range(2000, 5000);
> > +
> > +	drm_dp_read_dpcd_caps(&mtk_dp->aux, mtk_dp->rx_cap);
> > +
> > +	mtk_dp->rx_cap[DP_TRAINING_AUX_RD_INTERVAL] &=
> > DP_TRAINING_AUX_RD_MASK;
> > +
> > +	train_info->link_rate = min_t(int, mtk_dp->max_linkrate,
> > +				      mtk_dp->rx_cap[mtk_dp-
> > > max_linkrate]);
> > 
> > +	train_info->lane_count = min_t(int, mtk_dp->max_lanes,
> > +				       drm_dp_max_lane_count(mtk_dp-
> > > rx_cap));
> > 
> > +
> > +	train_info->tps3 = drm_dp_tps3_supported(mtk_dp->rx_cap);
> > +	train_info->tps4 = drm_dp_tps4_supported(mtk_dp->rx_cap);
> > +
> > +	train_info->sink_ssc = !!(mtk_dp->rx_cap[DP_MAX_DOWNSPREAD] &
> > +				  DP_MAX_DOWNSPREAD_0_5);
> 
> I think this is redundant because next statement would set sink_scc
> to
> false.
> 
> Regards,
> CK
> 

Hello Ck,

I will remove "train_info->sink_ssc = false;"

BRs,
Bo-Chen
> > +
> > +	train_info->sink_ssc = false;
> > +
> > +	drm_dp_dpcd_readb(&mtk_dp->aux, DP_MSTM_CAP, &val);
> > +	if (val & DP_MST_CAP) {
> > +		/* Clear DP_DEVICE_SERVICE_IRQ_VECTOR_ESI0 */
> > +		drm_dp_dpcd_readb(&mtk_dp->aux,
> > +				  DP_DEVICE_SERVICE_IRQ_VECTOR_ESI0,
> > &val);
> > +		if (val)
> > +			drm_dp_dpcd_writeb(&mtk_dp->aux,
> > +					   DP_DEVICE_SERVICE_IRQ_VECTOR
> > _ESI0,
> > +					   val);
> > +	}
> > +
> > +	return 0;
> > +}
> 
>