On Thu, Dec 8, 2022 at 2:24 AM Herve Codina <herve.codina@xxxxxxxxxxx> wrote: > > Hi Rob, > > On Wed, 7 Dec 2022 16:19:42 -0600 > Rob Herring <robh+dt@xxxxxxxxxx> wrote: > > > On Wed, Dec 7, 2022 at 10:24 AM Herve Codina <herve.codina@xxxxxxxxxxx> wrote: > > > > > > Hi, > > > > > > This series add support for the Renesas USBF controller (USB Device > > > Controller) available in the Renesas RZ/N1 SoC. > > > > > > Based on previous review: > > > https://lore.kernel.org/all/20221114111513.1436165-3-herve.codina@xxxxxxxxxxx/ > > > > > > A new strategy is proposed to handle the H2MODE bit from CFG_USB > > > register compared to the previous versions on the series. As a > > > reminder, H2MODE bit allows to configure the internal USB Port > > > interface for two hosts or one host and one device. > > > > Is this case any different from all the phandle properties we have in > > bindings that point to some misc registers somewhere else you need to > > poke? If so, I'm not really a fan of duplicating the information. > > Our case is that there is a bit in a register that affect several > devices. This bit must be set before the devices are started. > If this bit is changed while affected devices are running, system > hangs can occurs (datasheet). > > So, in order to do that we need the device in charge to set > this bit (sysctrl) to set this bit before other devices (USBF > and PCI bridge) were started. That sounds like you just need some platform level initialization and you are working around the desire to not have platform level initialization. Why doesn't/can't the bootloader initialize this? Seems like it might want to use PCI or USB too. > At sysctrl level, the bit is set during the probe() call. > The property 'depends-on' aim is to ensure the probe() calls > order between provider (sysctrl) and consumers (USBF and PCI > bridge). > > regmap and syscon are used to export registers from one device > to an other and the probe() calls order is not ensured by the > core or regmap infrastructure. Indeed, the regmap provider > probe() will not be called if the regmap provider was not probed > before the consumer ask for the regmap. > https://elixir.bootlin.com/linux/latest/source/drivers/mfd/syscon.c#L152 > https://elixir.bootlin.com/linux/latest/source/drivers/mfd/syscon.c#L43 > No specific action synchronisation are done with regmap/syscon > other than the regmap creation itself. Oh right. That's in place of course to avoid probe ordering issues... > I don't think the regmap/syscon will help in our case. > > > > > We also have cases of of_find_compatible_node(NULL, NULL, > > "foo-bar-syscon") which is a dependency expressed in the driver, but > > not DT. In either case, adding 'depends-on' would be an ABI break as > > you are requiring a DT change. > > In order to avoid the DT change, I can keep the 'depends-on' > optional in the PCI bridge binding. > This will be functionnal as sysctrl is already used in this node > (power-domain = <&sysctrl>). The relationship is already present > with this power-domain link. > > If ok, I will do this change in v4 series. I agree with Geert that this shouldn't be needed. Rob
