Re: [PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after plug in lookup failed

From	Thierry Reding <treding@nvidia.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after plug in lookup failed
Date	2015-09-03 11:10 +0200
Message-ID	<q4yGS-7v1-9@gated-at.bofh.it> (permalink)
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On Thu, Sep 03, 2015 at 12:27:47PM +0800, Yakir Yang wrote:
> Hi Rob,
> 
> 在 09/03/2015 04:17 AM, Rob Herring 写道:
> >On Tue, Sep 1, 2015 at 1:14 AM, Yakir Yang <ykk@rock-chips.com> wrote:
> >>Some edp screen do not have hpd signal, so we can't just return
> >>failed when hpd plug in detect failed.
> >This is a property of the panel (or connector perhaps), so this
> >property should be located there. At least, it is a common issue and
> >not specific to this chip. We could have an HDMI connector and failed
> >to hook up HPD for example. A connector node is also where hpd-gpios
> >should be located instead (and are already defined by
> >../bindings/video/hdmi-connector.txt). Perhaps we need a eDP connector
> >binding, too.
> 
> Yep, I agree with your front point, it is a property of panel, not specific
> to eDP controller, so this code should handle in connector logic.

From your description it sounds more like this is in fact a property of
the panel. Or maybe I should say "quirk". If the panel doesn't generate
the HPD signal, then that should be a property of the panel, not the
connector. The eDP specification mandates that connectors have a HPD
signal, though it allows the "HPD conductor in the connector cable" to
be omitted if not used by the source. I'd consider the cable to belong
to the panel rather than the connector, so absence of HPD, either
because the cable doesn't have the conductor or because the panel does
not generate the signal, should be a quirk of the panel.

That said you could have a panel that supports HPD connected via a cable
that doesn't transmit it, so this would be a per-board variant and hence
should be a device tree property rather than hard-coded in some panel
driver.

Conversely, if the panel isn't capable of generating an HPD signal, then
I don't think it would be appropriate to make it a DT property. It would
be better to hard-code it in the driver, lest someone forget to set the
property in DT and get stuck with a device that isn't operational.

Thierry

Thread

[PATCH v4 0/16] Add Analogix Core Display Port Driver Yakir Yang <ykk@rock-chips.com> - 2015-09-01 07:50 +0200
  [PATCH v4 01/16] drm: exynos/dp: fix code style Yakir Yang <ykk@rock-chips.com> - 2015-09-01 07:50 +0200
    Re: [PATCH v4 01/16] drm: exynos/dp: fix code style Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2015-09-03 02:30 +0200
      Re: [PATCH v4 01/16] drm: exynos/dp: fix code style Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2015-09-03 07:10 +0200
        Re: [PATCH v4 01/16] drm: exynos/dp: fix code style Yakir Yang <ykk@rock-chips.com> - 2015-09-03 07:40 +0200
          Re: [PATCH v4 01/16] drm: exynos/dp: fix code style Joe Perches <joe@perches.com> - 2015-09-03 08:00 +0200
            Re: [PATCH v4 01/16] drm: exynos/dp: fix code style Yakir Yang <ykk@rock-chips.com> - 2015-09-06 03:40 +0200
      Re: [PATCH v4 01/16] drm: exynos/dp: fix code style Yakir Yang <ykk@rock-chips.com> - 2015-09-03 07:10 +0200
  [PATCH v4 04/16] drm: bridge: analogix/dp: remove duplicate configuration of link rate and link count Yakir Yang <ykk@rock-chips.com> - 2015-09-01 08:00 +0200
  [PATCH v4 05/16] drm: bridge: analogix/dp: dynamic parse sync_pol & interlace & colorimetry Yakir Yang <ykk@rock-chips.com> - 2015-09-01 08:00 +0200
    Re: [PATCH v4 05/16] drm: bridge: analogix/dp: dynamic parse sync_pol  & interlace & colorimetry Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2015-09-03 10:10 +0200
      Re: [PATCH v4 05/16] drm: bridge: analogix/dp: dynamic parse sync_pol  & interlace & colorimetry Yakir Yang <ykk@rock-chips.com> - 2015-09-06 04:10 +0200
  [PATCH v4 11/16] drm: bridge: analogix/dp: add platform device type support Yakir Yang <ykk@rock-chips.com> - 2015-09-01 08:10 +0200
    Re: [PATCH v4 11/16] drm: bridge: analogix/dp: add platform device  type support Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2015-09-04 02:40 +0200
      Re: [PATCH v4 11/16] drm: bridge: analogix/dp: add platform device  type support Yakir Yang <ykk@rock-chips.com> - 2015-09-06 06:10 +0200
        Re: [PATCH v4 11/16] drm: bridge: analogix/dp: add platform device  type support Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2015-09-07 02:00 +0200
          Re: [PATCH v4 11/16] drm: bridge: analogix/dp: add platform device  type support Yakir Yang <ykk@rock-chips.com> - 2015-09-07 03:50 +0200
  [PATCH v4 08/16] drm: rockchip/dp: add rockchip platform dp driver Yakir Yang <ykk@rock-chips.com> - 2015-09-01 08:10 +0200
    Re: [PATCH v4 08/16] drm: rockchip/dp: add rockchip platform dp driver Heiko Stuebner <heiko@sntech.de> - 2015-09-01 16:30 +0200
      Re: [PATCH v4 08/16] drm: rockchip/dp: add rockchip platform dp  driver Yakir Yang <ykk@rock-chips.com> - 2015-09-01 16:50 +0200
    Re: [PATCH v4 08/16] drm: rockchip/dp: add rockchip platform dp driver Heiko Stuebner <heiko@sntech.de> - 2015-09-01 23:10 +0200
      Re: [PATCH v4 08/16] drm: rockchip/dp: add rockchip platform dp driver Yakir Yang <ykk@rock-chips.com> - 2015-09-02 04:00 +0200
  [PATCH v4 06/16] Documentation: drm/bridge: add document for analogix_dp Yakir Yang <ykk@rock-chips.com> - 2015-09-01 08:10 +0200
  [PATCH v4 09/16] drm: rockchip: add bpc and color mode setting Yakir Yang <ykk@rock-chips.com> - 2015-09-01 08:10 +0200
    Re: [PATCH v4 09/16] drm: rockchip: add bpc and color mode setting Heiko Stuebner <heiko@sntech.de> - 2015-09-01 23:10 +0200
      Re: [PATCH v4 09/16] drm: rockchip: add bpc and color mode setting Yakir Yang <ykk@rock-chips.com> - 2015-09-02 04:10 +0200
        Re: [PATCH v4 09/16] drm: rockchip: add bpc and color mode setting Thierry Reding <treding@nvidia.com> - 2015-09-02 10:40 +0200
          Re: [PATCH v4 09/16] drm: rockchip: add bpc and color mode setting Yakir Yang <ykk@rock-chips.com> - 2015-09-02 12:10 +0200
            Re: [PATCH v4 09/16] drm: rockchip: add bpc and color mode setting Thierry Reding <treding@nvidia.com> - 2015-09-03 10:40 +0200
              Re: [PATCH v4 09/16] drm: rockchip: add bpc and color mode setting Yakir Yang <ykk@rock-chips.com> - 2015-09-06 04:10 +0200
  [PATCH v4 10/16] phy: Add driver for rockchip Display Port PHY Yakir Yang <ykk@rock-chips.com> - 2015-09-01 08:10 +0200
    Re: [PATCH v4 10/16] phy: Add driver for rockchip Display Port PHY Heiko Stuebner <heiko@sntech.de> - 2015-09-01 19:00 +0200
      Re: [PATCH v4 10/16] phy: Add driver for rockchip Display Port PHY Heiko Stuebner <heiko@sntech.de> - 2015-09-01 23:00 +0200
        Re: [PATCH v4 10/16] phy: Add driver for rockchip Display Port PHY Yakir Yang <ykk@rock-chips.com> - 2015-09-02 03:50 +0200
      Re: [PATCH v4 10/16] phy: Add driver for rockchip Display Port PHY Yakir Yang <ykk@rock-chips.com> - 2015-09-02 03:10 +0200
    Re: [PATCH v4 10/16] phy: Add driver for rockchip Display Port PHY Rob Herring <robherring2@gmail.com> - 2015-09-02 15:30 +0200
      Re: [PATCH v4 10/16] phy: Add driver for rockchip Display Port PHY Yakir Yang <ykk@rock-chips.com> - 2015-09-03 05:30 +0200
        Re: [PATCH v4 10/16] phy: Add driver for rockchip Display Port PHY Heiko Stuebner <heiko@sntech.de> - 2015-09-03 16:00 +0200
  [PATCH v4 07/16] ARM: dts: exynos/dp: remove some properties that deprecated by analogix_dp driver Yakir Yang <ykk@rock-chips.com> - 2015-09-01 08:10 +0200
    Re: [PATCH v4 07/16] ARM: dts: exynos/dp: remove some properties that  deprecated by analogix_dp driver Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2015-09-03 02:10 +0200
  [PATCH v4 15/16] drm: bridge: analogix/dp: move hpd detect to connector detect function Yakir Yang <ykk@rock-chips.com> - 2015-09-01 08:20 +0200
  [PATCH v4 12/16] drm: bridge: analogix/dp: add some rk3288 special registers setting Yakir Yang <ykk@rock-chips.com> - 2015-09-01 08:20 +0200
  [PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after plug in lookup failed Yakir Yang <ykk@rock-chips.com> - 2015-09-01 08:20 +0200
    Re: [PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after  plug in lookup failed Rob Herring <robherring2@gmail.com> - 2015-09-02 22:20 +0200
      Re: [PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after  plug in lookup failed Yakir Yang <ykk@rock-chips.com> - 2015-09-03 06:30 +0200
        Re: [PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after  plug in lookup failed Thierry Reding <treding@nvidia.com> - 2015-09-03 11:10 +0200
          Re: [PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after  plug in lookup failed Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-09-04 12:30 +0200
          Re: [PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after  plug in lookup failed Thierry Reding <treding@nvidia.com> - 2015-09-07 10:30 +0200
        Re: [PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after  plug in lookup failed Rob Herring <robherring2@gmail.com> - 2015-09-04 23:50 +0200
          Re: [PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after  plug in lookup failed Yakir Yang <ykk@rock-chips.com> - 2015-09-06 10:30 +0200
            Re: [PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after  plug in lookup failed Thierry Reding <treding@nvidia.com> - 2015-09-07 10:40 +0200
      Re: [PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after  plug in lookup failed Thierry Reding <treding@nvidia.com> - 2015-09-03 10:50 +0200
        Re: [PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after  plug in lookup failed Rob Herring <robherring2@gmail.com> - 2015-09-04 00:00 +0200
          Re: [PATCH v4 14/16] drm: bridge: analogix/dp: try force hpd after  plug in lookup failed Thierry Reding <treding@nvidia.com> - 2015-09-04 12:10 +0200
  [PATCH v4 13/16] drm: bridge: analogix/dp: add max link rate and lane count limit for RK3288 Yakir Yang <ykk@rock-chips.com> - 2015-09-01 08:20 +0200
  [PATCH v4 16/16] drm: bridge: analogix/dp: add edid modes parse in get_modes method Yakir Yang <ykk@rock-chips.com> - 2015-09-01 08:30 +0200
  Re: [PATCH v4 03/16] drm: bridge: analogix/dp: split exynos dp driver to bridge dir Heiko Stuebner <heiko@sntech.de> - 2015-09-01 22:50 +0200
    Re: [PATCH v4 03/16] drm: bridge: analogix/dp: split exynos dp driver  to bridge dir Yakir Yang <ykk@rock-chips.com> - 2015-09-02 03:50 +0200
    Re: [PATCH v4 03/16] drm: bridge: analogix/dp: split exynos dp driver  to bridge dir Rob Herring <robherring2@gmail.com> - 2015-09-04 23:10 +0200
      Re: [PATCH v4 03/16] drm: bridge: analogix/dp: split exynos dp driver to bridge dir Heiko Stuebner <heiko@sntech.de> - 2015-09-04 23:40 +0200
        Re: [PATCH v4 03/16] drm: bridge: analogix/dp: split exynos dp  driver to bridge dir Thierry Reding <treding@nvidia.com> - 2015-09-07 10:20 +0200
  Re: [PATCH v4 0/16] Add Analogix Core Display Port Driver Heiko Stuebner <heiko@sntech.de> - 2015-09-02 00:20 +0200
    Re: [PATCH v4 0/16] Add Analogix Core Display Port Driver Yakir Yang <ykk@rock-chips.com> - 2015-09-02 04:20 +0200
  Re: [PATCH v4 03/16] drm: bridge: analogix/dp: split exynos dp driver  to bridge dir Emil Velikov <emil.l.velikov@gmail.com> - 2015-09-02 17:00 +0200
    Re: [PATCH v4 03/16] drm: bridge: analogix/dp: split exynos dp driver  to bridge dir Yakir Yang <ykk@rock-chips.com> - 2015-09-03 06:00 +0200
  Re: [PATCH v4 03/16] drm: bridge: analogix/dp: split exynos dp driver  to bridge dir Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2015-09-03 03:00 +0200
    Re: [PATCH v4 03/16] drm: bridge: analogix/dp: split exynos dp driver  to bridge dir Yakir Yang <ykk@rock-chips.com> - 2015-09-03 07:40 +0200
      Re: [PATCH v4 03/16] drm: bridge: analogix/dp: split exynos dp driver  to bridge dir Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2015-09-04 02:50 +0200
        Re: [PATCH v4 03/16] drm: bridge: analogix/dp: split exynos dp driver  to bridge dir Yakir Yang <ykk@rock-chips.com> - 2015-09-06 10:00 +0200
          Re: [PATCH v4 03/16] drm: bridge: analogix/dp: split exynos dp driver  to bridge dir Krzysztof Kozlowski <k.kozlowski@samsung.com> - 2015-09-07 02:30 +0200
            Re: [PATCH v4 03/16] drm: bridge: analogix/dp: split exynos dp driver  to bridge dir Yakir Yang <ykk@rock-chips.com> - 2015-09-07 04:30 +0200

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