On 12/2/2022 4:27 AM, Bjorn Andersson wrote: > On Wed, Oct 05, 2022 at 02:36:58PM +0530, Akhil P Oommen wrote: > @Ulf, Akhil has a power-domain for a piece of hardware which may be > voted active by multiple different subsystems (co-processors/execution > contexts) in the system. > > As such, during the powering down sequence we don't wait for the > power-domain to turn off. But in the event of an error, the recovery > mechanism relies on waiting for the hardware to settle in a powered off > state. > > The proposal here is to use the reset framework to wait for this state > to be reached, before continuing with the recovery mechanism in the > client driver. > > Given our other discussions on quirky behavior, do you have any > input/suggestions on this? > >> Some clients like adreno gpu driver would like to ensure that its gdsc >> is collapsed at hardware during a gpu reset sequence. This is because it >> has a votable gdsc which could be ON due to a vote from another subsystem >> like tz, hyp etc or due to an internal hardware signal. To allow >> this, gpucc driver can expose an interface to the client driver using >> reset framework. Using this the client driver can trigger a polling within >> the gdsc driver. > @Akhil, this description is fairly generic. As we've reached the state > where the hardware has settled and we return to the client, what > prevents it from being powered up again? > > Or is it simply a question of it hitting the powered-off state, not > necessarily staying there? Correct. It doesn't need to stay there. The intention is to hit the powered-off state at least once to clear all the internal hw states (basically a hw reset). -Akhil. > > Regards, > Bjorn > >> This series is rebased on top of qcom/linux:for-next branch. >> >> Related discussion: https://patchwork.freedesktop.org/patch/493144/ >> >> Changes in v7: >> - Update commit message (Bjorn) >> - Rebased on top of qcom/linux:for-next branch. >> >> Changes in v6: >> - No code changes in this version. Just captured the Acked-by tags >> >> Changes in v5: >> - Nit: Remove a duplicate blank line (Krzysztof) >> >> Changes in v4: >> - Update gpu dt-binding schema >> - Typo fix in commit text >> >> Changes in v3: >> - Use pointer to const for "struct qcom_reset_ops" in qcom_reset_map (Krzysztof) >> >> Changes in v2: >> - Return error when a particular custom reset op is not implemented. (Dmitry) >> >> Akhil P Oommen (6): >> dt-bindings: clk: qcom: Support gpu cx gdsc reset >> clk: qcom: Allow custom reset ops >> clk: qcom: gdsc: Add a reset op to poll gdsc collapse >> clk: qcom: gpucc-sc7280: Add cx collapse reset support >> dt-bindings: drm/msm/gpu: Add optional resets >> arm64: dts: qcom: sc7280: Add Reset support for gpu >> >> .../devicetree/bindings/display/msm/gpu.yaml | 6 +++++ >> arch/arm64/boot/dts/qcom/sc7280.dtsi | 3 +++ >> drivers/clk/qcom/gdsc.c | 23 ++++++++++++++---- >> drivers/clk/qcom/gdsc.h | 7 ++++++ >> drivers/clk/qcom/gpucc-sc7280.c | 10 ++++++++ >> drivers/clk/qcom/reset.c | 27 +++++++++++++++++++++- >> drivers/clk/qcom/reset.h | 8 +++++++ >> include/dt-bindings/clock/qcom,gpucc-sc7280.h | 3 +++ >> 8 files changed, 82 insertions(+), 5 deletions(-) >> >> -- >> 2.7.4 >>
