From: Andy Shevchenko <andriy.shevchenko@linux.intel.com> To: Chen-Yu Tsai <wenst@chromium.org> Cc: Rob Herring <robh+dt@kernel.org>, Frank Rowand <frowand.list@gmail.com>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>, Matthias Brugger <matthias.bgg@gmail.com>, AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>, Wolfram Sang <wsa@kernel.org>, Benson Leung <bleung@chromium.org>, Tzung-Bi Shih <tzungbi@kernel.org>, chrome-platform@lists.linux.dev, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, Douglas Anderson <dianders@chromium.org>, Johan Hovold <johan@kernel.org>, Hsin-Yi Wang <hsinyi@chromium.org>, Dmitry Torokhov <dmitry.torokhov@gmail.com>, Jiri Kosina <jikos@kernel.org>, linus.walleij@linaro.org, broonie@kernel.org, gregkh@linuxfoundation.org, hdegoede@redhat.com, james.clark@arm.com, james@equiv.tech, keescook@chromium.org, rafael@kernel.org, tglx@linutronix.de, Jeff LaBundy <jeff@labundy.com>, linux-input@vger.kernel.org, linux-i2c@vger.kernel.org Subject: Re: [RFC PATCH v3 3/5] platform/chrome: Introduce device tree hardware prober Date: Tue, 28 Nov 2023 18:25:47 +0200 [thread overview] Message-ID: <ZWYUi3Q5ptQXR0uQ@smile.fi.intel.com> (raw) In-Reply-To: <20231128084236.157152-4-wenst@chromium.org> On Tue, Nov 28, 2023 at 04:42:32PM +0800, Chen-Yu Tsai wrote: > Some devices are designed and manufactured with some components having > multiple drop-in replacement options. These components are often > connected to the mainboard via ribbon cables, having the same signals > and pin assignments across all options. These may include the display > panel and touchscreen on laptops and tablets, and the trackpad on > laptops. Sometimes which component option is used in a particular device > can be detected by some firmware provided identifier, other times that > information is not available, and the kernel has to try to probe each > device. > > This change attempts to make the "probe each device" case cleaner. The > current approach is to have all options added and enabled in the device > tree. The kernel would then bind each device and run each driver's probe > function. This works, but has been broken before due to the introduction > of asynchronous probing, causing multiple instances requesting "shared" > resources, such as pinmuxes, GPIO pins, interrupt lines, at the same > time, with only one instance succeeding. Work arounds for these include > moving the pinmux to the parent I2C controller, using GPIO hogs or > pinmux settings to keep the GPIO pins in some fixed configuration, and > requesting the interrupt line very late. Such configurations can be seen > on the MT8183 Krane Chromebook tablets, and the Qualcomm sc8280xp-based > Lenovo Thinkpad 13S. > > Instead of this delicate dance between drivers and device tree quirks, > this change introduces a simple I2C component prober. For any given > class of devices on the same I2C bus, it will go through all of them, > doing a simple I2C read transfer and see which one of them responds. > It will then enable the device that responds. > > This requires some minor modifications in the existing device tree. > The status for all the device nodes for the component options must be > set to "failed-needs-probe". This makes it clear that some mechanism is > needed to enable one of them, and also prevents the prober and device > drivers running at the same time. ... > +#include <linux/array_size.h> > +#include <linux/i2c.h> > +#include <linux/of.h> > +#include <linux/platform_device.h> init.h for init calls. > +static int chromeos_of_hw_prober_probe(struct platform_device *pdev) > +{ > + for (size_t i = 0; i < ARRAY_SIZE(hw_prober_platforms); i++) > + if (of_machine_is_compatible(hw_prober_platforms[i].compatible)) { > + int ret; Perhaps if (!of_machine_is_compatible(hw_prober_platforms[i].compatible)) continue; ? > + ret = hw_prober_platforms[i].prober(&pdev->dev, > + hw_prober_platforms[i].data); > + if (ret) > + return ret; > + } > + > + return 0; > +} -- With Best Regards, Andy Shevchenko
WARNING: multiple messages have this Message-ID (diff)
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com> To: Chen-Yu Tsai <wenst@chromium.org> Cc: Rob Herring <robh+dt@kernel.org>, Frank Rowand <frowand.list@gmail.com>, Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, Conor Dooley <conor+dt@kernel.org>, Matthias Brugger <matthias.bgg@gmail.com>, AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>, Wolfram Sang <wsa@kernel.org>, Benson Leung <bleung@chromium.org>, Tzung-Bi Shih <tzungbi@kernel.org>, chrome-platform@lists.linux.dev, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, Douglas Anderson <dianders@chromium.org>, Johan Hovold <johan@kernel.org>, Hsin-Yi Wang <hsinyi@chromium.org>, Dmitry Torokhov <dmitry.torokhov@gmail.com>, Jiri Kosina <jikos@kernel.org>, linus.walleij@linaro.org, broonie@kernel.org, gregkh@linuxfoundation.org, hdegoede@redhat.com, james.clark@arm.com, james@equiv.tech, keescook@chromium.org, rafael@kernel.org, tglx@linutronix.de, Jeff LaBundy <jeff@labundy.com>, linux-input@vger.kernel.org, linux-i2c@vger.kernel.org Subject: Re: [RFC PATCH v3 3/5] platform/chrome: Introduce device tree hardware prober Date: Tue, 28 Nov 2023 18:25:47 +0200 [thread overview] Message-ID: <ZWYUi3Q5ptQXR0uQ@smile.fi.intel.com> (raw) In-Reply-To: <20231128084236.157152-4-wenst@chromium.org> On Tue, Nov 28, 2023 at 04:42:32PM +0800, Chen-Yu Tsai wrote: > Some devices are designed and manufactured with some components having > multiple drop-in replacement options. These components are often > connected to the mainboard via ribbon cables, having the same signals > and pin assignments across all options. These may include the display > panel and touchscreen on laptops and tablets, and the trackpad on > laptops. Sometimes which component option is used in a particular device > can be detected by some firmware provided identifier, other times that > information is not available, and the kernel has to try to probe each > device. > > This change attempts to make the "probe each device" case cleaner. The > current approach is to have all options added and enabled in the device > tree. The kernel would then bind each device and run each driver's probe > function. This works, but has been broken before due to the introduction > of asynchronous probing, causing multiple instances requesting "shared" > resources, such as pinmuxes, GPIO pins, interrupt lines, at the same > time, with only one instance succeeding. Work arounds for these include > moving the pinmux to the parent I2C controller, using GPIO hogs or > pinmux settings to keep the GPIO pins in some fixed configuration, and > requesting the interrupt line very late. Such configurations can be seen > on the MT8183 Krane Chromebook tablets, and the Qualcomm sc8280xp-based > Lenovo Thinkpad 13S. > > Instead of this delicate dance between drivers and device tree quirks, > this change introduces a simple I2C component prober. For any given > class of devices on the same I2C bus, it will go through all of them, > doing a simple I2C read transfer and see which one of them responds. > It will then enable the device that responds. > > This requires some minor modifications in the existing device tree. > The status for all the device nodes for the component options must be > set to "failed-needs-probe". This makes it clear that some mechanism is > needed to enable one of them, and also prevents the prober and device > drivers running at the same time. ... > +#include <linux/array_size.h> > +#include <linux/i2c.h> > +#include <linux/of.h> > +#include <linux/platform_device.h> init.h for init calls. > +static int chromeos_of_hw_prober_probe(struct platform_device *pdev) > +{ > + for (size_t i = 0; i < ARRAY_SIZE(hw_prober_platforms); i++) > + if (of_machine_is_compatible(hw_prober_platforms[i].compatible)) { > + int ret; Perhaps if (!of_machine_is_compatible(hw_prober_platforms[i].compatible)) continue; ? > + ret = hw_prober_platforms[i].prober(&pdev->dev, > + hw_prober_platforms[i].data); > + if (ret) > + return ret; > + } > + > + return 0; > +} -- With Best Regards, Andy Shevchenko _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-11-28 16:26 UTC|newest] Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-11-28 8:42 [RFC PATCH v3 0/5] platform/chrome: Introduce DT hardware prober Chen-Yu Tsai 2023-11-28 8:42 ` Chen-Yu Tsai 2023-11-28 8:42 ` [RFC PATCH v3 1/5] of: dynamic: Add of_changeset_update_prop_string Chen-Yu Tsai 2023-11-28 8:42 ` Chen-Yu Tsai 2023-12-02 0:56 ` Doug Anderson 2023-12-02 0:56 ` Doug Anderson 2023-12-04 6:28 ` Chen-Yu Tsai 2023-12-04 6:28 ` Chen-Yu Tsai 2023-11-28 8:42 ` [RFC PATCH v3 2/5] i2c: of: Introduce component probe function Chen-Yu Tsai 2023-11-28 8:42 ` Chen-Yu Tsai 2023-11-28 16:22 ` Andy Shevchenko 2023-11-28 16:22 ` Andy Shevchenko 2023-11-29 8:20 ` Chen-Yu Tsai 2023-11-29 8:20 ` Chen-Yu Tsai 2023-12-02 0:57 ` Doug Anderson 2023-12-02 0:57 ` Doug Anderson 2023-12-04 9:52 ` Chen-Yu Tsai 2023-12-04 9:52 ` Chen-Yu Tsai 2023-12-04 16:03 ` Doug Anderson 2023-12-04 16:03 ` Doug Anderson 2023-12-08 15:10 ` Rob Herring 2023-12-08 15:10 ` Rob Herring 2023-11-28 8:42 ` [RFC PATCH v3 3/5] platform/chrome: Introduce device tree hardware prober Chen-Yu Tsai 2023-11-28 8:42 ` Chen-Yu Tsai 2023-11-28 16:25 ` Andy Shevchenko [this message] 2023-11-28 16:25 ` Andy Shevchenko 2023-11-29 8:23 ` Chen-Yu Tsai 2023-11-29 8:23 ` Chen-Yu Tsai 2023-12-02 0:58 ` Doug Anderson 2023-12-02 0:58 ` Doug Anderson 2023-12-04 7:24 ` Chen-Yu Tsai 2023-12-04 7:24 ` Chen-Yu Tsai 2023-12-04 7:53 ` Chen-Yu Tsai 2023-12-04 7:53 ` Chen-Yu Tsai 2023-12-03 6:31 ` kernel test robot 2023-12-06 21:41 ` kernel test robot 2023-11-28 8:42 ` [RFC PATCH v3 4/5] arm64: dts: mediatek: mt8173-elm-hana: Mark touchscreens and trackpads as fail Chen-Yu Tsai 2023-11-28 8:42 ` Chen-Yu Tsai 2023-12-02 0:58 ` Doug Anderson 2023-12-02 0:58 ` Doug Anderson 2023-12-04 6:59 ` Chen-Yu Tsai 2023-12-04 6:59 ` Chen-Yu Tsai 2023-12-04 16:50 ` Doug Anderson 2023-12-04 16:50 ` Doug Anderson 2023-12-05 10:22 ` AngeloGioacchino Del Regno 2023-12-05 10:22 ` AngeloGioacchino Del Regno 2023-12-06 2:55 ` Chen-Yu Tsai 2023-12-06 2:55 ` Chen-Yu Tsai 2023-12-06 10:02 ` AngeloGioacchino Del Regno 2023-12-06 10:02 ` AngeloGioacchino Del Regno 2023-12-06 17:00 ` Doug Anderson 2023-12-06 17:00 ` Doug Anderson 2023-11-28 8:42 ` [RFC PATCH v3 5/5] arm64: dts: mediatek: mt8173-elm-hana: Add G2touch G7500 touchscreen Chen-Yu Tsai 2023-11-28 8:42 ` Chen-Yu Tsai
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