On Tue, 17 Aug 2021 at 16:03, Thierry Reding thierry.reding@gmail.com wrote:
On Tue, Aug 17, 2021 at 02:04:38PM +0200, Ulf Hansson wrote:
On Tue, 17 Aug 2021 at 03:30, Dmitry Osipenko digetx@gmail.com wrote:
Add runtime PM and OPP support to the Host1x driver. It's required for enabling system-wide DVFS and supporting dynamic power management using a generic power domain. For the starter we will keep host1x always-on because dynamic power management require a major refactoring of the driver code since lot's of code paths will need the RPM handling and we're going to remove some of these paths in the future. Host1x doesn't consume much power so it is good enough, we at least need to resume Host1x in order to initialize the power state.
Tested-by: Peter Geis pgwipeout@gmail.com # Ouya T30 Tested-by: Paul Fertser fercerpav@gmail.com # PAZ00 T20 Tested-by: Nicolas Chauvet kwizart@gmail.com # PAZ00 T20 and TK1 T124 Tested-by: Matt Merhar mattmerhar@protonmail.com # Ouya T30 Signed-off-by: Dmitry Osipenko digetx@gmail.com
[...]
static int host1x_probe(struct platform_device *pdev) { struct host1x *host; @@ -394,6 +423,10 @@ static int host1x_probe(struct platform_device *pdev) /* set common host1x device data */ platform_set_drvdata(pdev, host);
err = devm_tegra_core_dev_init_opp_table_simple(&pdev->dev);if (err)return err;host->regs = devm_ioremap_resource(&pdev->dev, regs); if (IS_ERR(host->regs)) return PTR_ERR(host->regs);@@ -423,12 +456,9 @@ static int host1x_probe(struct platform_device *pdev) return err; }
host->rst = devm_reset_control_get(&pdev->dev, "host1x");if (IS_ERR(host->rst)) {err = PTR_ERR(host->rst);dev_err(&pdev->dev, "failed to get reset: %d\n", err);
err = host1x_get_resets(host);if (err) return err;
} err = host1x_iommu_init(host); if (err < 0) {@@ -443,22 +473,10 @@ static int host1x_probe(struct platform_device *pdev) goto iommu_exit; }
err = clk_prepare_enable(host->clk);if (err < 0) {dev_err(&pdev->dev, "failed to enable clock\n");goto free_channels;}err = reset_control_deassert(host->rst);if (err < 0) {dev_err(&pdev->dev, "failed to deassert reset: %d\n", err);goto unprepare_disable;}Removing the clk_prepare_enable() and reset_control_deassert() from host1x_probe(), might not be a good idea. See more about why, below.
err = host1x_syncpt_init(host); if (err) { dev_err(&pdev->dev, "failed to initialize syncpts\n");
goto reset_assert;
goto free_channels; } err = host1x_intr_init(host, syncpt_irq);@@ -467,10 +485,14 @@ static int host1x_probe(struct platform_device *pdev) goto deinit_syncpt; }
host1x_debug_init(host);
pm_runtime_enable(&pdev->dev);
if (host->info->has_hypervisor)host1x_setup_sid_table(host);
/* the driver's code isn't ready yet for the dynamic RPM */err = pm_runtime_resume_and_get(&pdev->dev);If the driver is being built with the CONFIG_PM Kconfig option being unset, pm_runtime_resume_and_get() will return 0 to indicate success - and without calling the ->runtime_resume() callback. In other words, the clock will remain gated and the reset will not be deasserted, likely causing the driver to be malfunctioning.
If the driver isn't ever being built with CONFIG_PM unset, feel free to ignore my above comments.
Otherwise, if it needs to work both with and without CONFIG_PM being set, you may use the following pattern in host1x_probe() to deploy runtime PM support:
"Enable the needed resources to probe the device" pm_runtime_get_noresume() pm_runtime_set_active() pm_runtime_enable()
"Before successfully completing probe" pm_runtime_put()
We made a conscious decision a few years ago to have ARCH_TEGRA select PM on both 32-bit and 64-bit ARM, specifically to avoid the need to do this dance (though there are still a few drivers left that do this, I think).
So I think this should be unnecessary. Unless perhaps if the sysfs PM controls have any influence on this. As far as I know, as long as the PM kconfig option is enabled, the sysfs control only influence the runtime behaviour (i.e. setting the sysfs PM control to "on" is going to force runtime PM to be resumed) but there's no way to disable runtime PM altogether via sysfs that would make the above necessary.
Thanks for clarifying! As I said, feel free to ignore my comments then.
For this and the other patches in the series, I assume you only need to care about whether the driver is a cross SoC driver and used on other platforms than Tegra then.
Thierry
Kind regards Uffe