On Sat, Sep 10, 2016 at 08:12:32PM +0200, Hans de Goede wrote: > Hi, > > On 09-09-16 23:41, Rob Herring wrote: > >On Thu, Sep 1, 2016 at 2:08 PM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > >>Allwinnner A13 / A23 / A33 based Q8 tablets are popular cheap 7" tablets > >>of which a new batch is produced every few weeks. Each batch uses a > >>different mix of touchscreen, accelerometer and wifi peripherals. > >> > >>Given that each batch is different creating a devicetree for each variant > >>is not desirable. This commit adds a Q8 tablet hardware manager which > >>auto-detects the touchscreen and accelerometer so that a single generic > >>dts can be used for these tablets. > >> > >>The wifi is connected to a discoverable bus (sdio or usb) and will be > >>autodetected by the mmc resp. usb subsystems. > >> > >>Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> > >>--- > >> .../misc/allwinner,sunxi-q8-hardwaremgr.txt | 52 +++ > >> drivers/misc/Kconfig | 12 + > >> drivers/misc/Makefile | 1 + > >> drivers/misc/q8-hardwaremgr.c | 512 +++++++++++++++++++++ > >> 4 files changed, 577 insertions(+) > >> create mode 100644 Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt > >> create mode 100644 drivers/misc/q8-hardwaremgr.c > >> > >>diff --git a/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt b/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt > >>new file mode 100644 > >>index 0000000..f428bf5 > >>--- /dev/null > >>+++ b/Documentation/devicetree/bindings/misc/allwinner,sunxi-q8-hardwaremgr.txt > >>@@ -0,0 +1,52 @@ > >>+Q8 tablet hardware manager > >>+-------------------------- > >>+ > >>+Allwinnner A13 / A23 / A33 based Q8 tablets are popular cheap 7" tablets of > >>+which a new batch is produced every few weeks. Each batch uses a different > >>+mix of touchscreen, accelerometer and wifi peripherals. > >>+ > >>+Given that each batch is different creating a devicetree for each variant is > >>+not desirable. The Q8 tablet hardware manager bindings are bindings for an os > >>+module which auto-detects the touchscreen so that a single > >>+generic dts can be used for these tablets. > >>+ > >>+The wifi is connected to a discoverable bus and will be autodetected by the os. > >>+ > >>+Required properties: > >>+ - compatible : "allwinner,sunxi-q8-hardwaremgr" > >>+ - touchscreen : phandle of a template touchscreen node, this must be a > >>+ child node of the touchscreen i2c bus > >>+ > >>+Optional properties: > >>+ - touchscreen-supply : regulator phandle for the touchscreen vdd supply > > > >While I said I think you should be using overlays here, you could also > >do it without. > > Good, because I believe that doing things without overlays will > be much easier. If you look at the actual implementation you will > see that it sets a lot of properties (touchscreen width, height, > inversion, axis-swapping, firmware-name) based on various sources, > the explosion of possible overlays from this is huge, and if > we're going to runtime patch the overlays then why use them at all > and not just runtime generate all the info ? That's fine if run-time makes more sense. I'd just like to move in the direction of applying a hunk of changes rather than C code creating nodes and properties one-by-one. > >However, this node has to go. It is not h/w, and you > >are putting it here purely to instantiate a driver. > > With "this" in "this node has to go", do you mean the node > with the "allwinner,sunxi-q8-hardwaremgr" compatible, or > do you mean the touchscreen template node ? Given that this binding section above is concerning allwinner,sunxi-q8-hardwaremgr, that is what I'm referring to. > > >For the > >touchscreen property, surely you know where the touchscreen is located > >in the DT? > > Nope q8 tablets come with A13, A23 or A33 SoCs, A23/A33 are pin > compatible with each other, but the A13 is not, this leads to > the touchscreen being on a different i2c bus, so I cannot hardcode > things, likewise the power-gpios and interrupt found in the > touchscreen node differ between the A13 vs A23/A33. Either the touchscreen node name is "touchscreen" or you can have compatible string for q8-touchscreen and use of_find_node_by_name or of_find_compatible_node. Doesn't matter what bus it is on. It only requires that there is only 1 node. > I actually had a touchscreen-i2c-bus property containing a > phandle to the i2c controller for the bus which has the > touchscreen in an earlier revision + touchscreen-gpios > and touchscreen-supply properties, I can switch to that > if you prefer that over having a touchscreen template node. > > > If not, of_find_node_by_name()? > > Still a bit confused about what you do not like, > (touchscreen template node vs q8-hardwaremgr node). > > I guess (based on context) you do not want the > q8-hardwaremgr node ? > > So the q8-hardwaremgr code should activate based on > the machine compatible I presume? Either that, or if you have the board specific compatible in the touchscreen node, then you could have a driver for it. That driver would need to probe the device and then create the "real" device. > How does that > work with module autoloading ? Can't non-DT based platform drivers do autoloading? Regardless, not really my problem from a binding perspective. > If you do not want the q8-hardwaremgr node and thus > no touchscreen property them yes I can use > of_find_node_by_name(), but I thought that was > generally frowned up on? Generally we do prefer finding things by compatible strings. But there are exceptions and doing fix-ups like this is a good example. > >For touchscreen-supply, I > >assume this is to turn on the supply so you can talk to the touch > >controller. There's no reason the supply can't just be in the > >touchscreen node itself. > > Only a few q8 tablets actually use the regulator, so > the hardwaremgr first tries detecting the touchscreen > without it, and only if it does not find anything then > tries with it, and adds a property to the touchscreen > node for it, but I guess I can do this other way > around and have it be present in the (incomplete / > template) touchscreen node and delete it from it if > not necessary. Right. 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