On Fri, Jun 16, 2017 at 10:33 AM, Mika Westerberg <[email protected]> wrote: > On Thu, Jun 15, 2017 at 06:01:02PM +0000, Gabriele Paoloni wrote: >> Hi Mika >> >> > -----Original Message----- >> > From: [email protected] [mailto:linux-pci- >> > [email protected]] On Behalf Of Mika Westerberg >> > Sent: 13 June 2017 21:04 >> > To: Gabriele Paoloni >> > Cc: Lorenzo Pieralisi; [email protected]; Rafael J. Wysocki; >> > [email protected]; [email protected]; [email protected]; >> > [email protected]; [email protected]; [email protected]; linux-arm- >> > [email protected]; [email protected]; >> > [email protected]; [email protected]; [email protected]; linux- >> > [email protected]; [email protected]; Linuxarm; linux- >> > [email protected]; [email protected]; John Garry; xuwei (O) >> > Subject: Re: [PATCH v9 5/7] ACPI: Translate the I/O range of non-MMIO >> > devices before scanning >> > >> > On Tue, Jun 13, 2017 at 07:01:38PM +0000, Gabriele Paoloni wrote: >> > > I am not very familiar with Linux MFD however the main issue here is >> > that >> > > 1) for IPMI we want to re-use the standard IPMI driver without >> > touching it: >> > > see >> > > >> > > static const struct acpi_device_id acpi_ipmi_match[] = { >> > > { "IPI0001", 0 }, >> > > { }, >> > > }; >> > > >> > > in "drivers/char/ipmi/ipmi_si_intf.c" (and in general any standard >> > driver >> > > of an LPC child) >> > > >> > > 2) We need a way to guarantee that all LPC children are not >> > enumerated >> > > by acpi_default_enumeration() (so for example if an ipmi node is >> > an LPC# >> > > child it should not be enumerated, otherwise it should be) >> > > Currently acpi_default_enumeration() skips spi/i2c slaves by >> > checking: >> > > 1) if the acpi resource type is a serial bus >> > > 2) if the type of serial bus descriptor is I2C or SPI >> > > >> > > For LPC we cannot leverage on any ACPI property to "recognize" >> > that our >> > > devices are LPC children; hence before I proposed for >> > acpi_default_enumeration() >> > > to skip devices that have already been enumerated (by calling >> > > acpi_device_enumerated() ). >> > > >> > > So in the current scenario, how do you think that MFD can help? >> > >> > If you look at Documentation/acpi/enumeration.txt there is a chapter >> > "MFD devices". I think it pretty much maches what you have here. An LPC >> > device (MFD device) and bunch of child devices. The driver for your LPC >> > device can specify _HID for each child device. Those are then mached by >> > the MFD ACPI code to the corresponding ACPI nodes from which platform >> > devices are created including "IPI0001". >> >> So I guess here in the LPC driver I would have an MFD cell for IPMI. I.e.: >> >> static struct mfd_cell_acpi_match hisi_lpc_ipmi_acpi_match = { >> .pnpid = "IPI0001", >> }; >> >> correct? > > Yes. > >> > >> > It causes acpi_default_enumeration() to be called but it should be fine >> > as we are dealing with platform device anyway. >> >> I do not quite understand how declaring such MFD cell above would make sure >> that the LPC probe is called before the IPMI device is enumerated... > > In fact it may be that it is not sufficient in this case because the > ACPI core might enumerate child devices before the LPC driver even gets > a chance to probe so you would need to add also scan handler to the > child devices and mark them already enumerated or something like that.
Or extend the special I2C/SPI handling to them. Thanks, Rafael
