linux-kernel - Re: [PATCH v5 00/10] drm: zynqmp_dp: IRQ cleanups and debugfs support

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Message-ID: <e5ca9be5-2918-427a-b7eb-28f1915b5d31@ideasonboard.com>
Date: Mon, 17 Jun 2024 10:47:08 +0300
From: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To: Sean Anderson <sean.anderson@...ux.dev>,
 Laurent Pinchart <laurent.pinchart@...asonboard.com>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 dri-devel@...ts.freedesktop.org
Cc: linux-arm-kernel@...ts.infradead.org, David Airlie <airlied@...il.com>,
 linux-kernel@...r.kernel.org, Daniel Vetter <daniel@...ll.ch>,
 Michal Simek <michal.simek@....com>
Subject: Re: [PATCH v5 00/10] drm: zynqmp_dp: IRQ cleanups and debugfs support

Hi Sean,

On 03/05/2024 22:29, Sean Anderson wrote:
> This series cleans up the zyqnmp_dp IRQ and locking situation. Once
> that's done, it adds debugfs support. The intent is to enable compliance
> testing or to help debug signal-integrity issues.
> 
> Last time I discussed converting the HPD work(s) to a threaded IRQ. I
> did not end up doing that for this series since the steps would be
> 
> - Add locking
> - Move link retraining to a work function
> - Harden the IRQ
> - Merge the works into a threaded IRQ (omitted)
> 
> Which with the exception of the final step is the same as leaving those
> works as-is. Conversion to a threaded IRQ can be done as a follow-up.

I tested this, and the "drm: zynqmp_dp: Convert to a hard IRQ" causes a 
hang for me when unloading the drivers. Unfortunately I'm not in the 
condition to debug it at the moment.

I have picked the first three patches into drm-misc-next, though, to 
decrease the number of patches in the series a bit. They looked 
independent and safe enough to apply.

  Tomi

> 
> Changes in v5:
> - Fix AUX bus not getting unregistered
> - Rebase onto drm-misc/drm-misc-next
> 
> Changes in v4:
> - Rebase onto drm/drm-next
> 
> Changes in v3:
> - Don't delay work
> - Convert to a hard IRQ
> - Use AUX IRQs instead of polling
> - Take dp->lock in zynqmp_dp_hpd_work_func
> 
> Changes in v2:
> - Rearrange zynqmp_dp for better padding
> - Split off the HPD IRQ work into another commit
> - Expand the commit message
> - Document hpd_irq_work
> - Document debugfs files
> - Add ignore_aux_errors and ignore_hpd debugfs files to replace earlier
>    implicit functionality
> - Attempt to fix unreproducable, spurious build warning
> - Drop "Optionally ignore DPCD errors" in favor of a debugfs file
>    directly affecting zynqmp_dp_aux_transfer.
> 
> Sean Anderson (10):
>    drm: zynqmp_kms: Fix AUX bus not getting unregistered
>    drm: zynqmp_dp: Rearrange zynqmp_dp for better padding
>    drm: zynqmp_dp: Don't delay work
>    drm: zynqmp_dp: Add locking
>    drm: zynqmp_dp: Don't retrain the link in our IRQ
>    drm: zynqmp_dp: Convert to a hard IRQ
>    drm: zynqmp_dp: Use AUX IRQs instead of polling
>    drm: zynqmp_dp: Split off several helper functions
>    drm: zynqmp_dp: Take dp->lock in zynqmp_dp_hpd_work_func
>    drm: zynqmp_dp: Add debugfs interface for compliance testing
> 
>   Documentation/gpu/drivers.rst     |   1 +
>   Documentation/gpu/zynqmp.rst      | 149 +++++
>   MAINTAINERS                       |   1 +
>   drivers/gpu/drm/xlnx/zynqmp_dp.c  | 883 +++++++++++++++++++++++++++---
>   drivers/gpu/drm/xlnx/zynqmp_kms.c |  12 +-
>   5 files changed, 977 insertions(+), 69 deletions(-)
>   create mode 100644 Documentation/gpu/zynqmp.rst
>