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Date: Mon, 20 Jan 2020 14:53:45 +0000
From: Steven Price <steven.price@....com>
To: Nicolas Boichat <drinkcat@...omium.org>,
Rob Herring <robh+dt@...nel.org>
Cc: Mark Rutland <mark.rutland@....com>, devicetree@...r.kernel.org,
Tomeu Vizoso <tomeu.vizoso@...labora.com>,
David Airlie <airlied@...ux.ie>, linux-kernel@...r.kernel.org,
Liam Girdwood <lgirdwood@...il.com>,
dri-devel@...ts.freedesktop.org, Mark Brown <broonie@...nel.org>,
linux-mediatek@...ts.infradead.org,
Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
hsinyi@...omium.org, Matthias Brugger <matthias.bgg@...il.com>,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 5/7] drm/panfrost: Add support for multiple power
domains
On 14/01/2020 07:16, Nicolas Boichat 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@...omium.org>
>
> ---
>
> 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
>
> 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 | 95 ++++++++++++++++++++--
> drivers/gpu/drm/panfrost/panfrost_device.h | 9 ++
> drivers/gpu/drm/panfrost/panfrost_drv.c | 1 +
> 3 files changed, 97 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/panfrost/panfrost_device.c b/drivers/gpu/drm/panfrost/panfrost_device.c
> index c30e0a3772a4f57..7c9766f76cc7689 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"
> @@ -119,6 +120,75 @@ 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;
> + }
> +
> + BUG_ON(num_domains > ARRAY_SIZE(pfdev->pm_domain_devs));
> +
> + for (i = 0; i < num_domains; i++) {
> + pfdev->pm_domain_devs[i] =
> + dev_pm_domain_attach_by_id(pfdev->dev, i);
> + if (IS_ERR(pfdev->pm_domain_devs[i])) {
> + err = PTR_ERR(pfdev->pm_domain_devs[i]);
> + pfdev->pm_domain_devs[i] = NULL;
> + dev_err(pfdev->dev,
> + "failed to get pm-domain %d: %d\n", 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);
> + if (!pfdev->pm_domain_links[i]) {
> + dev_err(pfdev->pm_domain_devs[i],
> + "adding device link failed!\n");
> + err = -ENODEV;
> + goto err;
> + }
> + }
> +
> + return 0;
> +
> +err:
> + panfrost_pm_domain_fini(pfdev);
> + return err;
> +}
> +
> int panfrost_device_init(struct panfrost_device *pfdev)
> {
> int err;
> @@ -149,37 +219,45 @@ int panfrost_device_init(struct panfrost_device *pfdev)
> goto err_out1;
> }
>
> + err = panfrost_pm_domain_init(pfdev);
> + if (err) {
> + dev_err(pfdev->dev, "pm_domain init failed %d\n", err);
No need for this print - panfrost_pm_domain_init() will output a (more
appropriate) error message on failure.
> + goto err_out2;
> + }
> +
> res = platform_get_resource(pfdev->pdev, IORESOURCE_MEM, 0);
> pfdev->iomem = devm_ioremap_resource(pfdev->dev, res);
> if (IS_ERR(pfdev->iomem)) {
> dev_err(pfdev->dev, "failed to ioremap iomem\n");
> err = PTR_ERR(pfdev->iomem);
> - goto err_out2;
> + goto err_out3;
> }
>
> err = panfrost_gpu_init(pfdev);
> if (err)
> - goto err_out2;
> + goto err_out3;
>
> err = panfrost_mmu_init(pfdev);
> if (err)
> - goto err_out3;
> + goto err_out4;
>
> err = panfrost_job_init(pfdev);
> if (err)
> - goto err_out4;
> + goto err_out5;
>
> err = panfrost_perfcnt_init(pfdev);
> if (err)
> - goto err_out5;
> + goto err_out6;
>
> return 0;
> -err_out5:
> +err_out6:
> panfrost_job_fini(pfdev);
> -err_out4:
> +err_out5:
> panfrost_mmu_fini(pfdev);
> -err_out3:
> +err_out4:
> panfrost_gpu_fini(pfdev);
> +err_out3:
> + panfrost_pm_domain_fini(pfdev);
> err_out2:
> panfrost_reset_fini(pfdev);
> err_out1:
> @@ -196,6 +274,7 @@ void panfrost_device_fini(struct panfrost_device *pfdev)
> panfrost_mmu_fini(pfdev);
> panfrost_gpu_fini(pfdev);
> panfrost_reset_fini(pfdev);
> + panfrost_pm_domain_fini(pfdev);
NIT: The reverse of the construction order would be to do this before
panfrost_reset_fini().
Otherwise this LGTM.
Thanks,
Steve
> panfrost_regulator_fini(pfdev);
> panfrost_clk_fini(pfdev);
> }
> diff --git a/drivers/gpu/drm/panfrost/panfrost_device.h b/drivers/gpu/drm/panfrost/panfrost_device.h
> index 021f063ffb3747f..143eab57180a2e1 100644
> --- 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 +62,11 @@ 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;
> };
>
> struct panfrost_device {
> @@ -73,6 +79,9 @@ 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 db3563b80150c9d..42b87e29e605149 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
> @@ -589,6 +589,7 @@ 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 */
> };
>
> static const struct of_device_id dt_match[] = {
>
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