On Tue, Feb 11, 2020 at 5:58 PM Rob Herring <robh+dt@xxxxxxxxxx> wrote: > > On Tue, Feb 11, 2020 at 2:09 PM Saravana Kannan <saravanak@xxxxxxxxxx> wrote: > > > > On Tue, Feb 11, 2020 at 11:44 AM Rob Herring <robh+dt@xxxxxxxxxx> wrote: > > > > > > +Saravana > > > > > > On Thu, Feb 6, 2020 at 11:27 PM Nicolas Boichat <drinkcat@xxxxxxxxxxxx> wrote: > > > > > > > > When there is a single power domain per device, the core will > > > > ensure the power domain is switched on (so it is technically > > > > equivalent to having not power domain specified at all). > > > > > > > > However, when there are multiple domains, as in MT8183 Bifrost > > > > GPU, we need to handle them in driver code. > > > > > > > > Signed-off-by: Nicolas Boichat <drinkcat@xxxxxxxxxxxx> > > > > > > > > --- > > > > > > > > The downstream driver we use on chromeos-4.19 currently uses 2 > > > > additional devices in device tree to accomodate for this [1], but > > > > I believe this solution is cleaner. > > > > > > > > [1] https://chromium.googlesource.com/chromiumos/third_party/kernel/+/refs/heads/chromeos-4.19/drivers/gpu/arm/midgard/platform/mediatek/mali_kbase_runtime_pm.c#31 > > > > > > > > v4: > > > > - Match the exact power domain names as specified in the compatible > > > > struct, instead of just matching the number of power domains. > > > > [Review: Ulf Hansson] > > > > - Dropped print and reordered function [Review: Steven Price] > > > > - nits: Run through latest version of checkpatch: > > > > - Use WARN instead of BUG_ON. > > > > - Drop braces for single expression if block. > > > > v3: > > > > - Use the compatible matching data to specify the number of power > > > > domains. Note that setting 0 or 1 in num_pm_domains is equivalent > > > > as the core will handle these 2 cases in the exact same way > > > > (automatically, without driver intervention), and there should > > > > be no adverse consequence in this case (the concern is about > > > > switching on only some power domains and not others). > > > > > > > > drivers/gpu/drm/panfrost/panfrost_device.c | 97 ++++++++++++++++++++-- > > > > drivers/gpu/drm/panfrost/panfrost_device.h | 11 +++ > > > > drivers/gpu/drm/panfrost/panfrost_drv.c | 2 + > > > > 3 files changed, 102 insertions(+), 8 deletions(-) > > > > > > > > diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c > > > > index 3720d50f6d9f965..8136babd3ba9935 100644 > > > > --- a/drivers/gpu/drm/panfrost/panfrost_device.c > > > > +++ b/drivers/gpu/drm/panfrost/panfrost_device.c > > > > @@ -5,6 +5,7 @@ > > > > #include <linux/clk.h> > > > > #include <linux/reset.h> > > > > #include <linux/platform_device.h> > > > > +#include <linux/pm_domain.h> > > > > #include <linux/regulator/consumer.h> > > > > > > > > #include "panfrost_device.h" > > > > @@ -120,6 +121,79 @@ static void panfrost_regulator_fini(struct panfrost_device *pfdev) > > > > pfdev->regulators); > > > > } > > > > > > > > +static void panfrost_pm_domain_fini(struct panfrost_device *pfdev) > > > > +{ > > > > + int i; > > > > + > > > > + for (i = 0; i < ARRAY_SIZE(pfdev->pm_domain_devs); i++) { > > > > + if (!pfdev->pm_domain_devs[i]) > > > > + break; > > > > + > > > > + if (pfdev->pm_domain_links[i]) > > > > + device_link_del(pfdev->pm_domain_links[i]); > > > > + > > > > + dev_pm_domain_detach(pfdev->pm_domain_devs[i], true); > > > > + } > > > > +} > > > > + > > > > +static int panfrost_pm_domain_init(struct panfrost_device *pfdev) > > > > +{ > > > > + int err; > > > > + int i, num_domains; > > > > + > > > > + num_domains = of_count_phandle_with_args(pfdev->dev->of_node, > > > > + "power-domains", > > > > + "#power-domain-cells"); > > > > + > > > > + /* > > > > + * Single domain is handled by the core, and, if only a single power > > > > + * the power domain is requested, the property is optional. > > > > + */ > > > > + if (num_domains < 2 && pfdev->comp->num_pm_domains < 2) > > > > + return 0; > > > > + > > > > + if (num_domains != pfdev->comp->num_pm_domains) { > > > > + dev_err(pfdev->dev, > > > > + "Incorrect number of power domains: %d provided, %d needed\n", > > > > + num_domains, pfdev->comp->num_pm_domains); > > > > + return -EINVAL; > > > > + } > > > > + > > > > + if (WARN(num_domains > ARRAY_SIZE(pfdev->pm_domain_devs), > > > > + "Too many supplies in compatible structure.\n")) > > > > + return -EINVAL; > > > > + > > > > + for (i = 0; i < num_domains; i++) { > > > > + pfdev->pm_domain_devs[i] = > > > > + dev_pm_domain_attach_by_name(pfdev->dev, > > > > + pfdev->comp->pm_domain_names[i]); > > > > + if (IS_ERR_OR_NULL(pfdev->pm_domain_devs[i])) { > > > > + err = PTR_ERR(pfdev->pm_domain_devs[i]) ? : -ENODATA; > > > > + pfdev->pm_domain_devs[i] = NULL; > > > > + dev_err(pfdev->dev, > > > > + "failed to get pm-domain %s(%d): %d\n", > > > > + pfdev->comp->pm_domain_names[i], i, err); > > > > + goto err; > > > > + } > > > > + > > > > + pfdev->pm_domain_links[i] = device_link_add(pfdev->dev, > > > > + pfdev->pm_domain_devs[i], DL_FLAG_PM_RUNTIME | > > > > + DL_FLAG_STATELESS | DL_FLAG_RPM_ACTIVE); > > > > > > We're in the process of adding device links based on DT properties. > > > Shouldn't we add power domains to that? See drivers/of/property.c for > > > what's handled. > > > > Rob, > > > > drivers/of/property.c doesn't enable the RPM_ACTIVE AND PM_RUNTIME > > flags. Wanted to start off conservative. > > I worry that you can't add it later without potentially breaking platforms. > > I haven't checked, but I assume these flags make runtime PM honor > device links? That seems like the more conservative option (more > reasons why a device can't suspend). Conservative as in, if of_devlink adds the RPM_ACTIVE flag, the drivers can't remove it. > > But adding command line ops > > to change the default flags shouldn't be difficult. But before I do > > that, I want to change of_devlink to > > fw_devlink=<disabled|permissive|enabled>. May be I can extend that to > > "disabled, permissive, suspend, runtime". > > I think any command line option should be debug primarily. It's kind > of a big hammer. It is a big hammer. But it's better than disabling of_devlink altogether. There is always going to be weird hardware that won't work with of_devlink if all the device link flags are set. They'll need some fix up of drivers and/or clean up of DT. And having different of_devlink command line options would at least let those hardware to run with as much of_devlink enabled as possible while working to get more fixes into the kernel. That way, we can make sure we don't regress further while trying to improve the support. > Can drivers adjust the flags themselves? Just modify the flags rather > than trying to create new links? They can, but only in an additive manner. And the way to do it would be to add a device link like usual and the framework takes care of combining the flags. That's why I don't set most of the flags by default. -Saravana
