[v12,0/5] drm/atomic-helper: Re-order CRTC and Bridge ops

Message

Aradhya Bhatia April 6, 2025, 1:16 p.m. UTC

Hello all,

This series re-orders the sequences in which the drm CRTC and the drm
Bridge get enabled and disabled with respect to each other.

The bridge pre_enable calls have been shifted before the crtc_enable and
the bridge post_disable calls have been shifted after the crtc_disable.

This has been done as per the definition of bridge pre_enable.
"The display pipe (i.e. clocks and timing signals) feeding this bridge will
not yet be running when this callback is called".

Since CRTC is also a source feeding the bridge, it should not be enabled
before the bridges in the pipeline are pre_enabled.

The original sequence. for display pipe enable looks like:

      crtc_enable

      bridge[n]_pre_enable
      ...
      bridge[1]_pre_enable

      encoder_enable

      bridge[1]_enable
      ...
      bridge[n]_enable

The sequence of enable after this patch-set will look like:

      bridge[n]_pre_enable
      ...
      bridge[1]_pre_enable

      crtc_enable
      encoder_enable

      bridge[1]_enable
      ...
      bridge[n]_enable


For the disable sequence, this is what the original looks like:

      bridge[n]_disable
      ...
      bridge[1]_disable

      encoder_disable

      bridge[1]_post_disable
      ...
      bridge[n]_post_disable

      crtc_disable
	        
This is what the disable sequence will be, after this series of patches:

      bridge[n]_disable
      ...
      bridge[1]_disable

      encoder_disable
      crtc_disable

      bridge[1]_post_disable
      ...
      bridge[n]_post_disable

This series further updates the bridge API definitions to accurately
reflect the updated scenario.

This series is a subset of its v11[0] which had 14 patches in the revision.
9 of those 14 patches (which were specific to the cdns-dsi bridge driver)
were merged[1].

Regards
Aradhya

---
* Note on checkpatch warning in patch 2/4 *
Patch 2/4 causes the checkpatch to flare up for 1 checkpatch 'check' -

CHECK: Lines should not end with a '('
#79: FILE: drivers/gpu/drm/drm_atomic_helper.c:1304:
+                       new_crtc_state = drm_atomic_get_new_crtc_state(

This patch is largely duplicating the original code, with minor differences to
perform different operations. This line of code pre-exists in the file and
have simply been duplicated. I have decided to keep it as is to maintain the
uniformity and the originally intended readability. Should perhaps a fix be
required, this patch/series is not the right place, and another patch can be
created to fix this across the whole file.

References:
[0]: Revision v11 of this series.
https://lore.kernel.org/all/[e-mail]/

[1]: Patches 1 through 9 getting merged.
https://lore.kernel.org/all/[e-mail]/


---
Change Log:

  - Changes in v12:
    - Drop patches 1 through 9 since they have been merged.
    - Rebase onto newer drm-misc-next.
    - Re-word the patch 3/4, ("drm/bridge: Update the bridge enable/disable doc")
      to make it more readable.

  - Changes in v11:
    - Add patch v11:13/14 ("drm/bridge: Update the bridge enable/disable doc"),
      that updates the documentation about the order of the various bridge
      enable/disable hooks being called wrt the CRTC and encoder hooks.
    - Rebase on drm-misc-next instead of linux-next.
      As part of rebase, accommodate the following change:
      - Change patch v10:08/13 ("drm/bridge: cdns-dsi: Support atomic bridge
        APIs") to v11:08/13 ("drm/bridge: cdns-dsi: Add input format
        negotiation"), since Maxime has already updated the bridge hooks to
        their atomic versions in commit 68c98e227a96 ("drm/bridge: cdns-csi:
        Switch to atomic helpers").
        My new patch now only adds the format negotiation hook for the cdns-dsi.
        (Note: Since the new patch is now only a subset of the old one, without
        any change in logic, I decided to carry forward the R-b and T-b tags.)
    - Add Alexander Sverdlin's T-b in patches 10, 11, 12.

  - Changes in v10:
    - Rebase on latest linux-next (next-20250226).
    - As part of rebase, update the patches to accommodate a couple of
      widespread changes in DRM Framework -
        - All the ("drm/atomic-helper: Change parameter name of ***") commits.
        - All the ("drm/bridge: Pass full state to ***") commits.
      (These updates are only trivial substitutions.)
    - Add Tomi Valkeinen's T-b tags in all the patches.

  - Changes in v9:
    - Fix the oops in 11/13 - where the encoder_bridge_enable _was_ pre_enabling
      the bridges instead of enabling.
    - Add the following tags:
      - Dmitry Baryshkov's R-b in patches 2, 10, 11, and A-b in patch 12.
      - Jayesh Choudhary's R-b in patch 12.
      - Tomi Valkeinen's R-b in patches 2, 10, 11, 12.

  - Changes in v8:
    - Move the phy de-initialization to bridge post_disable() instead of bridge
      disable() in patch-3.
    - Copy the private bridge state (dsi_cfg), in addition to the bridge_state,
      in patch-9.
    - Split patch v7:11/12 into three patches, v8:{10,11,12}/13, to separate out
      different refactorings into different patches, and improve bisectability.
    - Move patch v7:02/12 down to v8:06/12, to keep the initial patches for
      fixes only.
    - Drop patch v7:04/12 as it doesn't become relevant until patch v7:12/12.
    - Add R-b tags of Dmitry Baryshkov in patch-9 and patch-3, and of
      Tomi Valkeinen in patch-9.
   
  - Changes in v7:
    - phy_init()/exit() were called from the PM path in v6. Change it back to
      the bridge enable/disable path in patch-3, so that the phy_init() can go
      back to being called after D-Phy reset assert.
    - Reword commit text in patch-5 to explain the need of the fix.
    - Drop the stray code in patch-10.
    - Add R-b tag of Dmitry Baryshkov in patch-6.

  - Changes in v6:
    - Reword patch 3 to better explain the fixes around phy de-init.
    - Fix the Lane ready timeout condition in patch 7.
    - Fix the dsi _bridge_atomic_check() implementation by adding a new
      bridge state structure in patch 10.
    - Rework and combine patches v5:11/13 and v5:12/13 to v6:11/12.
    - Generate the patches of these series using the "patience" algorithm.
      Note: All patches, except v6:11/12, *do not* differ from their default
      (greedy) algorithm variants.
      For patch 11, the patience algorithm significantly improves the readability.
    - Rename and move the Bridge enable/disable enums from public to private
      in patch 11.
    - Add R-b tags of Tomi Valkeinen in patch 6, and Dmitry Baryshkov in patch 2.

  - Changes in v5:
    - Fix subject and description in patch 1/13.
    - Add patch to check the return value of
      phy_mipi_dphy_get_default_config() (patch: 6/13).
    - Change the Clk and Data Lane ready timeout from forever to 5s.
    - Print an error instead of calling WARN_ON_ONCE in patch 7/13.
    - Drop patch v4-07/11: "drm/bridge: cdns-dsi: Reset the DCS write FIFO".
      There has been some inconsistencies found with this patch upon further
      testing. This patch was being used to enable a DSI panel based on ILITEK
      ILI9881C bridge. This will be debugged separately.
    - Add patch to move the DSI mode check from _atomic_enable() to
      _atomic_check() (patch: 10/13).
    - Split patch v4-10/11 into 2 patches - 11/13 and 12/13.
      Patch 11/13 separates out the Encoder-Bridge operations into a helper
      function *without* changing the logic. Patch 12/13 then changes the order
      of the encoder-bridge operations as was intended in the original patch.
    - Add detailed comment for patch 13/13.
    - Add Tomi Valkeinen's R-b in patches 1, 2, 4, 5, 7, 8, 9, 13.

  - Changes in v4:
    - Add new patch, "drm/bridge: cdns-dsi: Move to devm_drm_of_get_bridge()",
      to update to an auto-managed way of finding next bridge in the chain.
    - Drop patch "drm/bridge: cdns-dsi: Fix the phy_initialized variable" and
      add "drm/bridge: cdns-dsi: Fix Phy _init() and _exit()" that properly
      de-initializes the Phy and maintains the initialization state.
    - Reword patch "drm/bridge: cdns-dsi: Reset the DCS write FIFO" to explain
      the HW concerns better.
    - Add R-b tag from Dmitry Baryshkov for patches 1/11 and 8/11.

  - Changes in v3:
    - Reword the commit message for patch "drm/bridge: cdns-dsi: Fix OF node
      pointer".
    - Add a new helper API to figure out DSI host input pixel format
      in patch "drm/mipi-dsi: Add helper to find input format".
    - Use a common function for bridge pre-enable and enable, and bridge disable
      and post-disable, to avoid code duplication.
    - Add T-b tag from Dominik Haller in patch 5/10. (Missed to add it in v2).
    - Add R-b tag from Dmitry Baryshkov for patch 8/10.

  - Changes in v2:
    - Drop patch "drm/tidss: Add CRTC mode_fixup"
    - Split patch "drm/bridge: cdns-dsi: Fix minor bugs" into 4 separate ones
    - Drop support for early_enable/late_disable APIs and instead re-order the
      pre_enable / post_disable APIs to be called before / after crtc_enable /
      crtc_disable.
    - Drop support for early_enable/late_disable in cdns-dsi and use
      pre_enable/post_disable APIs instead to do bridge enable/disable.


Previous versions:

v1:  https://lore.kernel.org/all/[e-mail]/
v2:  https://lore.kernel.org/all/[e-mail]/
v3:  https://lore.kernel.org/all/[e-mail]/
v4:  https://lore.kernel.org/all/[e-mail]/
v5:  https://lore.kernel.org/all/[e-mail]/
v6:  https://lore.kernel.org/all/[e-mail]/
v7:  https://lore.kernel.org/all/[e-mail]/
v8:  https://lore.kernel.org/all/[e-mail]/
v9:  https://lore.kernel.org/all/[e-mail]/
v10: https://lore.kernel.org/all/[e-mail]/
v11: https://lore.kernel.org/all/[e-mail]/

---

Aradhya Bhatia (5):
  drm/atomic-helper: Refactor crtc & encoder-bridge op loops into
    separate functions
  drm/atomic-helper: Separate out bridge pre_enable/post_disable from
    enable/disable
  drm/atomic-helper: Re-order bridge chain pre-enable and post-disable
  drm/bridge: Update the bridge enable/disable doc
  drm/bridge: cdns-dsi: Use pre_enable/post_disable to enable/disable

 .../gpu/drm/bridge/cadence/cdns-dsi-core.c    |  64 +++--
 drivers/gpu/drm/drm_atomic_helper.c           | 160 +++++++++--
 include/drm/drm_bridge.h                      | 249 +++++++++++++-----
 3 files changed, 355 insertions(+), 118 deletions(-)


base-commit: dd717762761807452ca25634652e180a80349cd8