linux-kernel - Re: [PATCH v17 4/8] drm: bridge: Cadence: Add MHDP8501 DP/HDMI 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: <wdelo4zco6v5qchdupfvbrqin4n7fyjyo6yaqbpfihdkkhceoi@ja4zxmhk5isq>
Date: Mon, 30 Sep 2024 10:18:06 +0200
From: Maxime Ripard <mripard@...nel.org>
To: Sandor Yu <sandor.yu@....com>, 
	"dmitry.baryshkov@...aro.org" <dmitry.baryshkov@...aro.org>
Cc: "andrzej.hajda@...el.com" <andrzej.hajda@...el.com>, 
	"neil.armstrong@...aro.org" <neil.armstrong@...aro.org>, Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
	"jonas@...boo.se" <jonas@...boo.se>, "jernej.skrabec@...il.com" <jernej.skrabec@...il.com>, 
	"airlied@...il.com" <airlied@...il.com>, "daniel@...ll.ch" <daniel@...ll.ch>, 
	"robh+dt@...nel.org" <robh+dt@...nel.org>, 
	"krzysztof.kozlowski+dt@...aro.org" <krzysztof.kozlowski+dt@...aro.org>, "shawnguo@...nel.org" <shawnguo@...nel.org>, 
	"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>, "festevam@...il.com" <festevam@...il.com>, 
	"vkoul@...nel.org" <vkoul@...nel.org>, 
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>, "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>, 
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"linux-phy@...ts.infradead.org" <linux-phy@...ts.infradead.org>, "kernel@...gutronix.de" <kernel@...gutronix.de>, 
	dl-linux-imx <linux-imx@....com>, Oliver Brown <oliver.brown@....com>, 
	"alexander.stein@...tq-group.com" <alexander.stein@...tq-group.com>, "sam@...nborg.org" <sam@...nborg.org>
Subject: Re: [PATCH v17 4/8] drm: bridge: Cadence: Add MHDP8501 DP/HDMI driver

On Sun, Sep 29, 2024 at 02:34:36AM GMT, Sandor Yu wrote:
> > > +static void cdns_hdmi_sink_config(struct cdns_mhdp8501_device *mhdp)
> > > +{
> > > +	struct drm_display_info *display = &mhdp->curr_conn->display_info;
> > > +	struct drm_connector_state *conn_state = mhdp->curr_conn->state;
> > 
> > That looks a bit hackish to me. We should probably provide a helper to get the
> > connector state the bridge is attached to.
> 
> How about code change to followed, is it more clear?
> 370         struct drm_connector *connector = mhdp->curr_conn;
> 371         struct drm_connector_state *conn_state = connector->state;
> 372         struct drm_display_info *display = &connector->display_info;
> 373         struct drm_scdc *scdc = &display->hdmi.scdc;

What I meant was that I wish bridges had a way to get their connector
pointer. It doesn't look like it's possible with drm_bridge_connector,
and we don't have access to drm_display_info anymore.

I don't really see a good way to do this yet, so maybe that kind of
workaround is ok. Eventually, I guess we'll have the scrambler setup in
the HDMI connector helpers anyway.

Dmitry, any idea?

> > > +static enum drm_mode_status
> > > +cdns_hdmi_tmds_char_rate_valid(const struct drm_bridge *bridge,
> > > +			       const struct drm_display_mode *mode,
> > > +			       unsigned long long tmds_rate) {
> > > +	struct cdns_mhdp8501_device *mhdp = bridge->driver_private;
> > > +	union phy_configure_opts phy_cfg;
> > > +	int ret;
> > > +
> > > +	phy_cfg.hdmi.tmds_char_rate = tmds_rate;
> > > +
> > > +	ret = phy_validate(mhdp->phy, PHY_MODE_HDMI, 0, &phy_cfg);
> > > +	if (ret < 0)
> > > +		return MODE_CLOCK_RANGE;
> > > +
> > > +	return MODE_OK;
> > > +}
> > > +
> > > +static enum drm_mode_status
> > > +cdns_hdmi_bridge_mode_valid(struct drm_bridge *bridge,
> > > +			    const struct drm_display_info *info,
> > > +			    const struct drm_display_mode *mode) {
> > > +	unsigned long long tmds_rate;
> > > +
> > > +	/* We don't support double-clocked and Interlaced modes */
> > > +	if (mode->flags & DRM_MODE_FLAG_DBLCLK ||
> > > +	    mode->flags & DRM_MODE_FLAG_INTERLACE)
> > > +		return MODE_BAD;
> > > +
> > > +	if (mode->hdisplay > 3840)
> > > +		return MODE_BAD_HVALUE;
> > > +
> > > +	if (mode->vdisplay > 2160)
> > > +		return MODE_BAD_VVALUE;
> > > +
> > > +	tmds_rate = mode->clock * 1000ULL;
> > > +	return cdns_hdmi_tmds_char_rate_valid(bridge, mode, tmds_rate); }
> > 
> > Didn't we agree on creating a mode_valid helper?
> 
> In fact, now I'm no idea where should add the mode_valid helper function.
> 
> In struct drm_bridge_funcs, it had mode_valid() and hdmi_tmds_char_rate_valid().
> 
> If create a new mode_valid helper function in struct drm_connector_hdmi_funcs,
> Is it appropriate to call another API function(tmds_char_rate_valid)
> at the same level within this API function?

I'm not quite sure what you mean, but a reasonable approach to me would
be to turn drm_hdmi_state_helper.c hdmi_clock_valid into a public
function, and then call it from drm_bridge_connector mode_valid hook.

It's a similar discussion to the previous one really: in order to
implement it properly, we need access to drm_display_info.

Maxime

Download attachment "signature.asc" of type "application/pgp-signature" (274 bytes)