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Tue, 28 Sep 2021 17:07:41 -0700 (PDT) Date: Tue, 28 Sep 2021 17:07:33 -0700 In-Reply-To: <20210929000735.585237-1-saravanak@google.com> Message-Id: <20210929000735.585237-2-saravanak@google.com> Mime-Version: 1.0 References: <20210929000735.585237-1-saravanak@google.com> X-Mailer: git-send-email 2.33.0.685.g46640cef36-goog Subject: [PATCH v4 1/2] drivers: bus: simple-pm-bus: Add support for probing simple bus only devices From: Saravana Kannan To: Russell King , Neil Armstrong , Geert Uytterhoeven , Magnus Damm , Tony Lindgren , Catalin Marinas , Will Deacon , Damien Le Moal , Greg Kroah-Hartman , Saravana Kannan Cc: Ulf Hansson , Rob Herring , kernel-team@android.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-oxnas@groups.io, linux-renesas-soc@vger.kernel.org, linux-omap@vger.kernel.org, linux-riscv@lists.infradead.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210928_170743_554478_8D027D80 X-CRM114-Status: GOOD ( 26.53 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org fw_devlink could end up creating device links for bus only devices. However, bus only devices don't get probed and can block probe() or sync_state() [1] call backs of other devices. To avoid this, probe these devices using the simple-pm-bus driver. However, there are instances of devices that are not simple buses (they get probed by their specific drivers) that also list the "simple-bus" (or other bus only compatible strings) in their compatible property to automatically populate their child devices. We still want these devices to get probed by their specific drivers. So, we make sure this driver only probes devices that are only buses. [1] - https://lore.kernel.org/lkml/CAPDyKFo9Bxremkb1dDrr4OcXSpE0keVze94Cm=zrkOVxHHxBmQ@mail.gmail.com/ Fixes: c442a0d18744 ("driver core: Set fw_devlink to "permissive" behavior by default") Signed-off-by: Saravana Kannan Tested-by: Saravana Kannan Tested-by: Ulf Hansson Tested-by: Geert Uytterhoeven --- drivers/bus/simple-pm-bus.c | 42 ++++++++++++++++++++++++++++++++++--- 1 file changed, 39 insertions(+), 3 deletions(-) diff --git a/drivers/bus/simple-pm-bus.c b/drivers/bus/simple-pm-bus.c index 01a3d0cd08ed..6b8d6257ed8a 100644 --- a/drivers/bus/simple-pm-bus.c +++ b/drivers/bus/simple-pm-bus.c @@ -13,11 +13,36 @@ #include #include - static int simple_pm_bus_probe(struct platform_device *pdev) { - const struct of_dev_auxdata *lookup = dev_get_platdata(&pdev->dev); - struct device_node *np = pdev->dev.of_node; + const struct device *dev = &pdev->dev; + const struct of_dev_auxdata *lookup = dev_get_platdata(dev); + struct device_node *np = dev->of_node; + const struct of_device_id *match; + + /* + * Allow user to use driver_override to bind this driver to a + * transparent bus device which has a different compatible string + * that's not listed in simple_pm_bus_of_match. We don't want to do any + * of the simple-pm-bus tasks for these devices, so return early. + */ + if (pdev->driver_override) + return 0; + + match = of_match_device(dev->driver->of_match_table, dev); + /* + * These are transparent bus devices (not simple-pm-bus matches) that + * have their child nodes populated automatically. So, don't need to + * do anything more. We only match with the device if this driver is + * the most specific match because we don't want to incorrectly bind to + * a device that has a more specific driver. + */ + if (match && match->data) { + if (of_property_match_string(np, "compatible", match->compatible) == 0) + return 0; + else + return -ENODEV; + } dev_dbg(&pdev->dev, "%s\n", __func__); @@ -31,14 +56,25 @@ static int simple_pm_bus_probe(struct platform_device *pdev) static int simple_pm_bus_remove(struct platform_device *pdev) { + const void *data = of_device_get_match_data(&pdev->dev); + + if (pdev->driver_override || data) + return 0; + dev_dbg(&pdev->dev, "%s\n", __func__); pm_runtime_disable(&pdev->dev); return 0; } +#define ONLY_BUS ((void *) 1) /* Match if the device is only a bus. */ + static const struct of_device_id simple_pm_bus_of_match[] = { { .compatible = "simple-pm-bus", }, + { .compatible = "simple-bus", .data = ONLY_BUS }, + { .compatible = "simple-mfd", .data = ONLY_BUS }, + { .compatible = "isa", .data = ONLY_BUS }, + { .compatible = "arm,amba-bus", .data = ONLY_BUS }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, simple_pm_bus_of_match);