[PATCH] acpi: device: Fix check for sequence number

[Simon Glass]

Hi Wolfgang,

On Thu, 13 Aug 2020 at 01:23, Wolfgang Wallner
<wolfgang.wallner at br-automation.com> wrote:
>
> Hi Simon,
>
> -----"Simon Glass" <sjg at chromium.org> schrieb: -----
> > Betreff: Re: [PATCH] acpi: device: Fix check for sequence number
> >
> > Hi Wolfgang,
> >
> > On Thu, 30 Jul 2020 at 06:47, Wolfgang Wallner
> > <wolfgang.wallner at br-automation.com> wrote:
> > >
> > > Currently the function acpi_check_seq() checks whether dev->req_seq is
> > > unequal to "-1", but it should actually check dev->seq. Change it to
> > > check dev->seq.
> > >
> > > For req_seq the value "-1" would be a valid (meaning 'any'), while for
> > > seq the value "-1" means 'none' and is not valid.
> > >
> > > Quoting the description of udevice in device.h:
> > >  * @req_seq: Requested sequence number for this device (-1 = any)
> > >  * @seq: Allocated sequence number for this device (-1 = none).
> > >  *       This is set up when the device is probed and will be unique
> > >  *       within the device's uclass.
> > >
> > > Signed-off-by: Wolfgang Wallner <wolfgang.wallner at br-automation.com>
> > >
> > > Fixes: commit fefac0b0643b ("dm: acpi: Enhance acpi_get_name()")
> > >
> > > ---
> > >
> > >  lib/acpi/acpi_device.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > >
> >
> > What problem are you seeing without this patch?
>
> I see the following warning: "Device 'serial at 18,2' has no seq".
>
> In my case req_seq for the UART is -1 ("any"), while seq is 0.
> Why would we check for req_seq and not for seq in this function?
>
> > At present the ACPI device may not always be probed, and probing is
> > when the sequence number is currently set up.
>
> In my case the UART is already probed before the ACPI tables are generated.

I would expect req_seq to be set to the UART number, i.e. the value of
the alias (uart0, uart1) that points to the node.

I wonder why that doesn't work in your case?

Are you sure that all UARTs are probed before ACPI tables are created?
Normally U-Boot would only probe the one being used for the console.

>
> >
> > I have been thinking about dropping req_seq and doing everything when
> > the device is bound, but haven't dug into it in detail yet.
>
> regards, Wolfgang

Regards,
Simon