Re: [PATCH v6 00/24] Associate ddc adapters with connectors

[Laurent Pinchart <laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org>]

On Tue, Jul 30, 2019 at 04:01:23PM +0100, Emil Velikov wrote:
> On 2019/07/26, Andrzej Pietrasiewicz wrote:
> > It is difficult for a user to know which of the i2c adapters is for which
> > drm connector. This series addresses this problem.
> > 
> > The idea is to have a symbolic link in connector's sysfs directory, e.g.:
> > 
> > ls -l /sys/class/drm/card0-HDMI-A-1/ddc
> > lrwxrwxrwx 1 root root 0 Jun 24 10:42 /sys/class/drm/card0-HDMI-A-1/ddc \
> > 	-> ../../../../soc/13880000.i2c/i2c-2
> > 
> > The user then knows that their card0-HDMI-A-1 uses i2c-2 and can e.g. run
> > ddcutil:
> > 
> > ddcutil -b 2 getvcp 0x10
> > VCP code 0x10 (Brightness): current value =    90, max value =   100
> > 
> > The first patch in the series adds struct i2c_adapter pointer to struct
> > drm_connector. If the field is used by a particular driver, then an
> > appropriate symbolic link is created by the generic code, which is also added
> > by this patch.
> > 
> > Patch 2 adds a new variant of drm_connector_init(), see the changelog
> > below.
> > 
> > Patches 3..24 are examples of how to convert a driver to this new scheme.
> > 
> > v1..v2:
> > 
> > - used fixed name "ddc" for the symbolic link in order to make it easy for
> > userspace to find the i2c adapter
> > 
> > v2..v3:
> > 
> > - converted as many drivers as possible.
> > 
> > v3..v4:
> > 
> > - added Reviewed-by for patch 01/23
> > - moved "ddc" field assignment to before drm_connector_init() is called
> > in msm, vc4, sti, mgag200, ast, amdgpu, radeon
> > - simplified the code in amdgpu and radeon at the expense of some lines
> > exceeding 80 characters as per Alex Deucher's suggestion
> > - added i915
> > 
> > v4..v5:
> > 
> > - changed "include <linux/i2c.h>" to "struct i2c_adapter;"
> > in drm_connector.h, consequently, added "include <linux/i2c.h>"
> > in drm_sysfs.c.
> > - added "drm_connector_init_with_ddc()" variant to ensure that the ddc
> > field of drm_connector is preserved accross its invocation
> > - accordingly changed invocations of drm_connector_init() in the
> > touched drivers to use the new variant
> > 
> > v5..v6:
> > 
> > - improved subject line of patch 1
> > - added kernel-doc for drm_connector_init_with_ddc()
> > - improved kernel-doc for the ddc field of struct drm_connector
> > - added Reviewed-by in patches 17 and 18
> > - added Acked-by in patch 2
> > - made the ownership of ddc i2c_adapter explicit in all patches,
> > this made the affected patches much simpler
> > 
> > @Benjamin
> > @Shawn
> > 
> > There were your Acked-by or Reviewed-by for some patches in v4, but now
> > that the patches use the newly added function I'm not sure I can still
> > include those tags without you actually confirming. Can I? Or can you
> > please re-review? 
> > 
> > TODO: nouveau, gma500, omapdrm, panel-simple - if applicable.
> > Other drivers are either already converted or don't mention neither
> > "ddc" nor "i2c_adapter".
> > 
> Another way to check is to look for drm_get_edid. Sadly that also
> highlights aux. dp/mst instances, which expose the DDC in another way.
> 
> For example comparing the diff stat wrt the following command shows
> git grep -wc drm_get_edid -- drivers/gpu/drm/

There's also drm_do_get_edid, which points to the adv7511 bridge as a
good candidate.

> > 
> >  .../gpu/drm/amd/amdgpu/amdgpu_connectors.c    |  96 ++++++++----
> drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_helpers.c:1
> - as pointed out by Alex - mix of aux dp/mst and normal
> 
> >  drivers/gpu/drm/ast/ast_mode.c                |  13 +-
> 
> drivers/gpu/drm/bridge/analogix-anx78xx.c:1
> drivers/gpu/drm/bridge/analogix/analogix_dp_core.c:1
> - not applicable: aux dp/mst
> 
> 
> >  drivers/gpu/drm/bridge/dumb-vga-dac.c         |   6 +-
> 
> drivers/gpu/drm/bridge/sii902x.c:1
> - normal instance(?) that should be updated at some point.
> 
> >  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c     |   6 +-
> 
> drivers/gpu/drm/bridge/tc358767.c:1
> - not applicable: aux dp/mst
> 
> >  drivers/gpu/drm/bridge/ti-tfp410.c            |   6 +-
> 
> drivers/gpu/drm/drm_dp_mst_topology.c:3
> - not applicable: aux dp/mst
> 
> >  drivers/gpu/drm/drm_connector.c               |  35 +++++
> >  drivers/gpu/drm/drm_sysfs.c                   |   8 +
> 
> drivers/gpu/drm/drm_edid.c:7
> drivers/gpu/drm/drm_probe_helper.c:1
> - unrelated
> 
> >  drivers/gpu/drm/exynos/exynos_hdmi.c          |   6 +-
> 
> drivers/gpu/drm/gma500/cdv_intel_dp.c:3
> drivers/gpu/drm/gma500/cdv_intel_hdmi.c:2
> drivers/gpu/drm/gma500/oaktrail_hdmi.c:1
> drivers/gpu/drm/gma500/oaktrail_lvds.c:2
> drivers/gpu/drm/gma500/psb_intel_modes.c:1
> drivers/gpu/drm/gma500/psb_intel_sdvo.c:2
> - should be updated at some point (as you pointed out).
> 
> >  drivers/gpu/drm/i915/display/intel_hdmi.c     |  12 +-
> drivers/gpu/drm/i915/intel_connector.c:1
> drivers/gpu/drm/i915/intel_crt.c:2
> - not too sure here
> 
> drivers/gpu/drm/i915/intel_dp.c:2
> - not applicable: aux dp/mst
> 
> drivers/gpu/drm/i915/intel_lvds.c:1
> drivers/gpu/drm/i915/intel_sdvo.c:2
> - not too sure here
> 
> 
> >  drivers/gpu/drm/imx/imx-ldb.c                 |   7 +-
> >  drivers/gpu/drm/imx/imx-tve.c                 |   6 +-
> >  drivers/gpu/drm/mediatek/mtk_hdmi.c           |   7 +-
> >  drivers/gpu/drm/mgag200/mgag200_mode.c        |  13 +-
> >  drivers/gpu/drm/msm/hdmi/hdmi_connector.c     |   6 +-
> drivers/gpu/drm/msm/edp/edp_ctrl.c:1
> - not applicable: aux dp/mst
> 
> drivers/gpu/drm/nouveau/nouveau_connector.c:2
> - should be updated at some point (as you pointed out).
> 
> 
> drivers/gpu/drm/panel/panel-simple.c:1
> - no applicable: panel driver
> 
> 
> >  drivers/gpu/drm/radeon/radeon_connectors.c    | 142 +++++++++++++-----
> >  drivers/gpu/drm/rockchip/inno_hdmi.c          |   6 +-
> >  drivers/gpu/drm/rockchip/rk3066_hdmi.c        |   7 +-
> >  drivers/gpu/drm/sti/sti_hdmi.c                |   6 +-
> >  drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c        |   7 +-
> >  drivers/gpu/drm/tegra/hdmi.c                  |   7 +-
> >  drivers/gpu/drm/tegra/sor.c                   |   7 +-
> 
> drivers/gpu/drm/tegra/output.c:1
> - already handled in hdmi/sor
> 
> >  drivers/gpu/drm/tilcdc/tilcdc_tfp410.c        |   6 +-
> >  drivers/gpu/drm/vc4/vc4_hdmi.c                |  12 +-
> >  drivers/gpu/drm/zte/zx_hdmi.c                 |   6 +-
> >  drivers/gpu/drm/zte/zx_vga.c                  |   6 +-
> >  include/drm/drm_connector.h                   |  18 +++
> >  26 files changed, 336 insertions(+), 121 deletions(-)
> 
> In a Tl;Dr: I think this series covers 90%+ of the existing rather huge) driverset.
> 
> For the series:
> Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
> 
> Fwiw I'm in favour of Jani's suggestion to fold the dcc into the usual
> helper drm_connector_init(). Although since we have 130+ instances it
> might be better left for another day.
> 
> HTH
> -Emil

-- 
Regards,

Laurent Pinchart
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