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Message-ID: <20151007091830.GE21513@n2100.arm.linux.org.uk> Date: Wed, 7 Oct 2015 10:18:30 +0100 From: Russell King - ARM Linux <linux@....linux.org.uk> To: Yakir Yang <ykk@...k-chips.com> Cc: linux-rockchip@...ts.infradead.org, dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, Fabio Estevam <fabio.estevam@...escale.com>, David Airlie <airlied@...ux.ie>, Sascha Hauer <s.hauer@...gutronix.de>, Philipp Zabel <p.zabel@...gutronix.de>, Andy Yan <andy.yan@...k-chips.com>, Jon Nettleton <jon.nettleton@...il.com> Subject: Re: [PATCH 08/12] drm: bridge/dw_hdmi: avoid enabling interface in mode_set On Wed, Oct 07, 2015 at 11:50:53AM +0800, Yakir Yang wrote: > > > On 08/09/2015 12:04 AM, Russell King wrote: > >On a mode set, DRM makes the following sequence of calls: > >* for_each_encoder > >* bridge mode_fixup > >* encoder mode_fixup > >* crtc mode_fixup > >* for_each_encoder > >* bridge disable > >* encoder prepare > >* bridge post_disable > >* disable unused encoders > >* crtc prepare > >* crtc mode_set > >* for_each_encoder > >* encoder mode_set > >* bridge mode_set > >* crtc commit > >* for_each_encoder > >* bridge pre_enable > >* encoder commit > >* bridge enable > > > >dw_hdmi enables the HDMI output in both the bridge mode_set() and also > >the bridge enable() step. This is duplicated work - we can avoid the > >setup in mode_set() and just do it in the enable() stage. This > >simplifies the code a little. > > > >Signed-off-by: Russell King <rmk+kernel@....linux.org.uk> > > I have noticed that dw_hdmi driver have poweron/poweroff when > driver detect HPD event in irq thread, that's also duplicated works, > would you like to collect that changes into this one: > > static irqreturn_t dw_hdmi_irq(int irq, void *dev_id) > { > ...... > > if (intr_stat & HDMI_IH_PHY_STAT0_HPD) { > if (phy_int_pol & HDMI_PHY_HPD) { > dev_dbg(hdmi->dev, "EVENT=plugin\n"); > > hdmi_modb(hdmi, 0, HDMI_PHY_HPD, HDMI_PHY_POL0); > > dw_hdmi_poweron(hdmi); // no need here > } else { > dev_dbg(hdmi->dev, "EVENT=plugout\n"); > > hdmi_modb(hdmi, HDMI_PHY_HPD, HDMI_PHY_HPD, > HDMI_PHY_POL0); > > dw_hdmi_poweroff(hdmi); // no need here > } > drm_helper_hpd_irq_event(hdmi->connector.dev); > } > ...... > } I'm very much of the opinion of making small logical changes. This patch is one small logical change to the DRM-side logic to get rid of the identified duplication there without touching anything else. If removing the above calls to dw_hdmi_poweron()/dw_hdmi_poweroff() were found to cause a regression, then the whole change would end up being reverted, which would be annoying. -- FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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