On Fri, Feb 7, 2020 at 10:26 PM Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
>
> On Fri, 7 Feb 2020 at 06:27, 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>
>
> Besides a minor nitpick, feel free to add:
>
> Reviewed-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
>
> Kind regards
> Uffe
>
> [snip]
> > +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"))
>
> Nitpick:
> Not sure this deserves a WARN. Perhaps a regular dev_err() is sufficient.
Ah well I had a BUG_ON before so presumably this is already a little better ,-)
You can only reach there if you set pfdev->comp->num_pm_domains >
MAX_PM_DOMAINS in the currently matched struct panfrost_compatible
(pfdev->comp->num_pm_domains == num_domains, and see below too), so
the kernel code would actually be actually broken (not the device
tree, nor anything that could be probed). So I'm wondering if the
loudness of a WARN is better in this case? Arguable ,-)
> > + return -EINVAL;
> [snip]
> > --- a/drivers/gpu/drm/panfrost/panfrost_device.h
> > +++ b/drivers/gpu/drm/panfrost/panfrost_device.h
> > @@ -21,6 +21,7 @@ struct panfrost_perfcnt;
> >
> > #define NUM_JOB_SLOTS 3
> > #define MAX_REGULATORS 2
> > +#define MAX_PM_DOMAINS 3
> >
> > struct panfrost_features {
> > u16 id;
> > @@ -61,6 +62,13 @@ struct panfrost_compatible {
> > /* Supplies count and names. */
> > int num_supplies;
> > const char * const *supply_names;
> > + /*
> > + * Number of power domains required, note that values 0 and 1 are
> > + * handled identically, as only values > 1 need special handling.
> > + */
> > + int num_pm_domains;
> > + /* Only required if num_pm_domains > 1. */
> > + const char * const *pm_domain_names;
> > };
> >
> > struct panfrost_device {
> > @@ -73,6 +81,9 @@ struct panfrost_device {
> > struct clk *bus_clock;
> > struct regulator_bulk_data regulators[MAX_REGULATORS];
> > struct reset_control *rstc;
> > + /* pm_domains for devices with more than one. */
> > + struct device *pm_domain_devs[MAX_PM_DOMAINS];
> > + struct device_link *pm_domain_links[MAX_PM_DOMAINS];
> >
> > struct panfrost_features features;
> > const struct panfrost_compatible *comp;
> > diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
> > index 4d08507526239f2..a6e162236d67fdf 100644
> > --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
> > +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
> > @@ -663,6 +663,8 @@ const char * const default_supplies[] = { "mali" };
> > static const struct panfrost_compatible default_data = {
> > .num_supplies = ARRAY_SIZE(default_supplies),
> > .supply_names = default_supplies,
> > + .num_pm_domains = 1, /* optional */
> > + .pm_domain_names = NULL,
> > };
> >
> > static const struct of_device_id dt_match[] = {
> > --
> > 2.25.0.341.g760bfbb309-goog
> >
