Re: [PATCH v5 00/12] Fix USB suspend on TI J7200 (cdns3-ti, cdns3, xhci)

[Roger Quadros <rogerq@kernel.org>]

Hi,

On 26/07/2024 21:17, Théo Lebrun wrote:
> Currently, system-wide suspend is broken on J7200 because of a
> controller reset. The TI wrapper does not get re-initialised at resume
> and the first register access from cdns core fails.
> 
> We address that in a few ways:
>  - In cdns3-ti, if a reset has occured at resume, we reconfigure the HW.
>  - We pass the XHCI_RESET_ON_RESUME quirk, meaning the XHCI core expects
>    a resume.

OK.
>  - We add a xhci->lost_power flag.

Why?

> 
> The previous revision had one big issue: we had to know if
> reset-on-resume was true, at probe-time. This is where the main

Don't we already know this at probe-time? why not just rely on the existing
XHCI_RESET_ON_RESUME qurik, than add a new mechanism?

> difference with previous revisions is. We now pass the information from
> wrapper devices back up into XHCI. The xhci->lost_power flag gets its
> default value from the XHCI_RESET_ON_RESUME quirk. It however allows
> wrappers to signal *at resume* if they still expect a reset.
> 
> That means wrappers that are unsure if they will reset should:
>  - (1) set the quirk at probe and,
>  - (2) potentially set xhci->lost_power to false at resume.
> 
> We implement that for cdns3, by piggybacking on the host role ->resume()
> callback already receives the information from its caller.
> 
> Have a nice day,
> Théo
> 
> Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
> ---
> Changes in v5:
> - dt-bindings: take Reviewed-by Rob and Conor for the first
>   patch: "dt-bindings: usb: ti,j721e-usb: fix compatible list".
> - cdns3-ti:
>   - We now do have HW init code inside cdns_ti_reset_and_init_hw().
>   - It gets called at probe unconditionally and from ->runtime_resume()
>     if a reset is detected (using the W1 register).
>   - Auxdata patches have been reworked now that there is default auxdata
>     since commit b50a2da03bd9 ("usb: cdns3-ti: Add workaround for
>     Errata i2409"). We now have a patch that moves auxdata to match
>     data: "usb: cdns3-ti: grab auxdata from match data".
> - cdns3/xhci: those are three new patches.
>   - First, we rename "hibernated" to "lost_power" in arguments to
>     the role ->resume() callbacks.
>   - Then we add the xhci->lost_power flag, and only have it always copy
>     the value from XHCI_RESET_ON_RESUME.
>   - Finally, we set the flag from the host role driver.
> - Link to v4: https://lore.kernel.org/lkml/20240307-j7200-usb-suspend-v4-0-5ec7615431f3@bootlin.com/
> 
> Changes in v4:
> - dt-bindings: usb: ti,j721e-usb:
>   - Remove ti,am64-usb single compatible entry.
>   - Reverse ordering of compatible pair j721e + am64
>     (becoming am64 + j721e).
>   - Add j7200 + j721e compatible pair (versus only j7200). It is the
>     same thing as am64: only the integration differs with base j721e
>     compatible.
>   - NOT taking trailers from Conor as patches changed substantially.
> - arm64: dts: ti: j3-j7200:
>   - Use j7200 + j721e compatible pair (versus only j7200 previously).
> - arm64: dts: ti: j3-am64:
>   - Fix to use am64 + j721e compatible pair (versus only am64).
>     This is a new patch.
> - Link to v3: https://lore.kernel.org/r/20240223-j7200-usb-suspend-v3-0-b41c9893a130@bootlin.com
> 
> Changes in v3:
> - dt-bindings: use an enum to list compatibles instead of the previous
>   odd construct. This is done in a separate patch from the one adding
>   J7200 compatible.
> - dt-bindings: dropped Acked-by Conor as the changes were modified a lot.
> - Add runtime PM back. Put the init sequence in ->runtime_resume(). It
>   gets called at probe for all compatibles and at resume for J7200.
> - Introduce a cdns_ti_match_data struct rather than rely on compatible
>   from code.
> - Reorder code changes. Add infrastructure based on match data THEN add
>   compatible and its match data.
> - DTSI: use only J7200 compatible rather than both J7200 then J721E.
> - Link to v2: https://lore.kernel.org/r/20231120-j7200-usb-suspend-v2-0-038c7e4a3df4@bootlin.com
> 
> Changes in v2:
> - Remove runtime PM from cdns3-ti; it brings nothing. That means our
>   cdns3-ti suspend/resume patch is simpler; there is no need to handle
>   runtime PM at suspend/resume.
> - Do not add cdns3 host role suspend/resume callbacks; they are not
>   needed as core detects reset on resume & calls cdns_drd_host_on when
>   needed.
> - cdns3-ti: Move usb2_refclk_rate_code assignment closer to the value
>   computation.
> - cdns3/host.c: do not pass XHCI_SUSPEND_RESUME_CLKS quirk to xHCI; it
>   is unneeded on our platform.
> - Link to v1: https://lore.kernel.org/r/20231113-j7200-usb-suspend-v1-0-ad1ee714835c@bootlin.com
> 
> ---
> Théo Lebrun (12):
>       dt-bindings: usb: ti,j721e-usb: fix compatible list
>       dt-bindings: usb: ti,j721e-usb: add ti,j7200-usb compatible
>       usb: cdns3-ti: move reg writes to separate function
>       usb: cdns3-ti: run HW init at resume() if HW was reset
>       usb: cdns3: add quirk to platform data for reset-on-resume
>       usb: cdns3-ti: grab auxdata from match data
>       usb: cdns3-ti: add J7200 support with reset-on-resume behavior
>       usb: cdns3: rename hibernated argument of role->resume() to lost_power
>       xhci: introduce xhci->lost_power flag
>       usb: cdns3: host: transmit lost_power signal from wrapper to XHCI
>       arm64: dts: ti: k3-j7200: use J7200-specific USB compatible
>       arm64: dts: ti: k3-am64: add USB fallback compatible to J721E
> 
>  .../devicetree/bindings/usb/ti,j721e-usb.yaml      |   5 +-
>  arch/arm64/boot/dts/ti/k3-am64-main.dtsi           |   2 +-
>  arch/arm64/boot/dts/ti/k3-j7200-main.dtsi          |   2 +-
>  drivers/usb/cdns3/cdns3-gadget.c                   |   4 +-
>  drivers/usb/cdns3/cdns3-ti.c                       | 151 ++++++++++++++-------
>  drivers/usb/cdns3/cdnsp-gadget.c                   |   2 +-
>  drivers/usb/cdns3/core.h                           |   3 +-
>  drivers/usb/cdns3/host.c                           |  13 ++
>  drivers/usb/host/xhci.c                            |   8 +-
>  drivers/usb/host/xhci.h                            |   6 +
>  10 files changed, 136 insertions(+), 60 deletions(-)
> ---
> base-commit: c33ffdb70cc6df4105160f991288e7d2567d7ffa
> change-id: 20240726-s2r-cdns-4b180cd960ff
> 
> Best regards,

-- 
cheers,
-roger