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Sun, 09 Feb 2020 23:51:01 -0800 (PST) MIME-Version: 1.0 References: <20200207052627.130118-1-drinkcat@chromium.org> <20200207052627.130118-6-drinkcat@chromium.org> In-Reply-To: From: Ulf Hansson Date: Mon, 10 Feb 2020 08:50:25 +0100 Message-ID: Subject: Re: [PATCH v4 5/7] drm/panfrost: Add support for multiple power domains To: Nicolas Boichat Cc: Rob Herring , David Airlie , Daniel Vetter , Mark Rutland , Matthias Brugger , Tomeu Vizoso , Steven Price , Alyssa Rosenzweig , Liam Girdwood , Mark Brown , dri-devel , DTML , Linux Kernel Mailing List , Linux ARM , "moderated list:ARM/Mediatek SoC support" , Hsin-Yi Wang Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 9 Feb 2020 at 13:50, Nicolas Boichat wrote: > > On Fri, Feb 7, 2020 at 10:26 PM Ulf Hansson wrote: > > > > On Fri, 7 Feb 2020 at 06:27, 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 > > > > Besides a minor nitpick, feel free to add: > > > > Reviewed-by: Ulf Hansson > > > > 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 ,-) I see. It's not a big a deal, so feel free to keep as is. [...] Kind regards Uffe