On Mon, 30 Apr 2018, John Garry wrote:
> On 30/04/2018 06:36, Lee Jones wrote:
> > On Fri, 27 Apr 2018, John Garry wrote:
> > > On 26/04/2018 15:23, John Garry wrote:
> > > > On 26/04/2018 15:08, Mika Westerberg wrote:
> > > > > On Thu, Apr 26, 2018 at 02:49:49PM +0100, John Garry wrote:
> > > > > > diff --git a/drivers/bus/hisi_lpc.c b/drivers/bus/hisi_lpc.c
> > > > > > index 2d4611e..b04425b 100644
> > > > > > --- a/drivers/bus/hisi_lpc.c
> > > > > > +++ b/drivers/bus/hisi_lpc.c
> > > > > > @@ -18,6 +18,8 @@
> > > > > > #include <linux/of_platform.h>
> > > > > > #include <linux/pci.h>
> > > > > > #include <linux/slab.h>
> > > > > > +#include <linux/serial_8250.h>
> > > > > > +#include "../tty/serial/8250/8250.h"
> > > > > >
> > > > > > #define DRV_NAME "hisi-lpc"
> > > > > >
> > > > > > @@ -345,6 +347,7 @@ static void hisi_lpc_comm_outs(void *hostdata,
> > > > > > unsigned
> > > > > > long pio,
> > > > > > #define MFD_CHILD_NAME_LEN (ACPI_ID_LEN +
> > > > > > sizeof(MFD_CHILD_NAME_PREFIX) -
> > > > > > 1)
> > > > > >
> > > > > > struct hisi_lpc_mfd_cell {
> > > > > > + struct plat_serial8250_port serial8250_port;
> > > > > > struct mfd_cell_acpi_match acpi_match;
> > > > > > char name[MFD_CHILD_NAME_LEN];
> > > > > > char pnpid[ACPI_ID_LEN];
> > > > > > @@ -513,10 +516,31 @@ static int hisi_lpc_acpi_probe(struct device
> > > > > > *hostdev)
> > > > > > dev_warn(&child->dev, "set resource fail (%d)\n", ret);
> > > > > > return ret;
> > > > > > }
> > > > > > + if (!strcmp(acpi_device_hid(child), "HISI1031")) {
> > > > >
> > > >
> > > > Hi Mika,
> > > >
> > > > > Hmm, there is a way in struct mfd_cell to match child devices using _HID
> > > > > so is there something preventing you from using that?
> > > >
> > > > Not that I know about. Can you describe this method? I guess I also
> > > > don't need to set the mfd_cell pnpid either for this special case device.
> > > >
> > >
> > > So we using the mfd_cell to match child devices using _HID. At a glance, I
> > > don't actually see other drivers to use mfd_cell_acpi_match.pnpid .
> > >
> > > Anyway we don't use static tables as we need to update the resources of the
> > > cell dynamically. However I do look at a driver like intel_quark_i2c_gpio.c,
> > > and this dynamically modifies the value of global mfd_cell array here:
> > > https://elixir.bootlin.com/linux/latest/source/drivers/mfd/intel_quark_i2c_gpio.c#L266
> > >
> > > I know the cell array is only used at probe time, but this did not look to
> > > be good standard practice to me.
> >
> > Lots of drivers do this to supply dynamic data. If there is no other
> > sane way of providing such data, it's fine to do. Although each
> > situation should be dealt with on a case-by-case basis.
> >
>
> Hi Lee,
>
> Thanks for your input.
>
> I do see others drivers which use dynamic mem for the mfd_cells (like
> cros_ec_dev.c), so what we're doing in this driver already is not totally
> unchartered territory. But creating the MFD cells from the ACPI table could
> be ...
Right. I don't normally like mixing platform data technologies (MFD,
ACPI and DT). I normally NACK patches which take information from
Device Tree and populate MFD cells with it. ACPI would be the same I
guess.
> Anyway, I'll cc you in my next patchset and maybe you can kindly check it.
>
--
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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