On 31/01/2020 16:59, Thierry Reding wrote:
> From: Thierry Reding <treding@xxxxxxxxxx>
>
> Commit fd67e9c6ed5a ("drm/tegra: Do not implement runtime PM") replaced
> the generic runtime PM usage by a host1x bus-specific implementation in
> order to work around some assumptions baked into runtime PM that are in
> conflict with the requirements in the Tegra DRM driver.
>
> Unfortunately the new runtime PM callbacks are not setup yet at the time
> when the SOR driver first needs to resume the device to register the SOR
> pad clock, and accesses to register will cause the system to hang.
>
> Note that this only happens on Tegra124 and Tegra210 because those are
> the only SoCs where the SOR pad clock is registered from the SOR driver.
> Later generations use a SOR pad clock provided by the BPMP.
>
> Fix this by moving the registration of the SOR pad clock after the
> host1x client has been registered. That's somewhat suboptimal because
> this could potentially, though it's very unlikely, cause the Tegra DRM
> to be probed if the SOR happens to be the last subdevice to register,
> only to be immediately removed again if the SOR pad output clock fails
> to register. That's just a minor annoyance, though, and doesn't justify
> implementing a workaround.
>
> Fixes: fd67e9c6ed5a ("drm/tegra: Do not implement runtime PM")
> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
> ---
> drivers/gpu/drm/tegra/sor.c | 32 +++++++++++++++++---------------
> 1 file changed, 17 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/gpu/drm/tegra/sor.c b/drivers/gpu/drm/tegra/sor.c
> index aa4e1695b537..81226a4953c1 100644
> --- a/drivers/gpu/drm/tegra/sor.c
> +++ b/drivers/gpu/drm/tegra/sor.c
> @@ -3915,6 +3915,17 @@ static int tegra_sor_probe(struct platform_device *pdev)
> platform_set_drvdata(pdev, sor);
> pm_runtime_enable(&pdev->dev);
>
> + INIT_LIST_HEAD(&sor->client.list);
> + sor->client.ops = &sor_client_ops;
> + sor->client.dev = &pdev->dev;
> +
> + err = host1x_client_register(&sor->client);
> + if (err < 0) {
> + dev_err(&pdev->dev, "failed to register host1x client: %d\n",
> + err);
> + goto rpm_disable;
> + }
> +
> /*
> * On Tegra210 and earlier, provide our own implementation for the
> * pad output clock.
> @@ -3926,13 +3937,13 @@ static int tegra_sor_probe(struct platform_device *pdev)
> sor->index);
> if (!name) {
> err = -ENOMEM;
> - goto rpm_disable;
> + goto unregister;
> }
>
> err = host1x_client_resume(&sor->client);
> if (err < 0) {
> dev_err(sor->dev, "failed to resume: %d\n", err);
> - goto rpm_disable;
> + goto unregister;
> }
>
> sor->clk_pad = tegra_clk_sor_pad_register(sor, name);
> @@ -3941,24 +3952,15 @@ static int tegra_sor_probe(struct platform_device *pdev)
>
> if (IS_ERR(sor->clk_pad)) {
> err = PTR_ERR(sor->clk_pad);
> - dev_err(&pdev->dev, "failed to register SOR pad clock: %d\n",
> + dev_err(sor->dev, "failed to register SOR pad clock: %d\n",
> err);
> - goto rpm_disable;
> - }
> -
> - INIT_LIST_HEAD(&sor->client.list);
> - sor->client.ops = &sor_client_ops;
> - sor->client.dev = &pdev->dev;
> -
> - err = host1x_client_register(&sor->client);
> - if (err < 0) {
> - dev_err(&pdev->dev, "failed to register host1x client: %d\n",
> - err);
> - goto rpm_disable;
> + goto unregister;
> }
>
> return 0;
>
> +unregister:
> + host1x_client_unregister(&sor->client);
> rpm_disable:
> pm_runtime_disable(&pdev->dev);
> remove:
>
Reviewed-by: Jon Hunter <jonathanh@xxxxxxxxxx>
Tested-by: Jon Hunter <jonathanh@xxxxxxxxxx>
Cheers
Jon
--
nvpublic
