Re: [PATCH 5.10 14/49] net: ipa: ignore CHANNEL_NOT_RUNNING errors

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Wed, Mar 10, 2021 at 11:06:09PM +0530, Naresh Kamboju wrote:
> On Wed, 10 Mar 2021 at 18:56, <gregkh@linuxfoundation.org> wrote:
> >
> > From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >
> > From: Alex Elder <elder@linaro.org>
> >
> > [ Upstream commit f849afcc8c3b27d7b50827e95b60557f24184df0 ]
> >
> > IPA v4.2 has a hardware quirk that requires the AP to allocate GSI
> > channels for the modem to use.  It is recommended that these modem
> > channels get stopped (with a HALT generic command) by the AP when
> > its IPA driver gets removed.
> >
> > The AP has no way of knowing the current state of a modem channel.
> > So when the IPA driver issues a HALT command it's possible the
> > channel is not running, and in that case we get an error indication.
> > This error simply means we didn't need to stop the channel, so we
> > can ignore it.
> >
> > This patch adds an explanation for this situation, and arranges for
> > this condition to *not* report an error message.
> >
> > Signed-off-by: Alex Elder <elder@linaro.org>
> > Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> > Signed-off-by: Sasha Levin <sashal@kernel.org>
> > ---
> >  drivers/net/ipa/gsi.c | 24 +++++++++++++++++++++++-
> >  1 file changed, 23 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ipa/gsi.c b/drivers/net/ipa/gsi.c
> > index 2a65efd3e8da..48ee43b89fec 100644
> > --- a/drivers/net/ipa/gsi.c
> > +++ b/drivers/net/ipa/gsi.c
> > @@ -1052,10 +1052,32 @@ static void gsi_isr_gp_int1(struct gsi *gsi)
> >         u32 result;
> >         u32 val;
> >
> > +       /* This interrupt is used to handle completions of the two GENERIC
> > +        * GSI commands.  We use these to allocate and halt channels on
> > +        * the modem's behalf due to a hardware quirk on IPA v4.2.  Once
> > +        * allocated, the modem "owns" these channels, and as a result we
> > +        * have no way of knowing the channel's state at any given time.
> > +        *
> > +        * It is recommended that we halt the modem channels we allocated
> > +        * when shutting down, but it's possible the channel isn't running
> > +        * at the time we issue the HALT command.  We'll get an error in
> > +        * that case, but it's harmless (the channel is already halted).
> > +        *
> > +        * For this reason, we silently ignore a CHANNEL_NOT_RUNNING error
> > +        * if we receive it.
> > +        */
> >         val = ioread32(gsi->virt + GSI_CNTXT_SCRATCH_0_OFFSET);
> >         result = u32_get_bits(val, GENERIC_EE_RESULT_FMASK);
> > -       if (result != GENERIC_EE_SUCCESS_FVAL)
> > +
> > +       switch (result) {
> > +       case GENERIC_EE_SUCCESS_FVAL:
> > +       case GENERIC_EE_CHANNEL_NOT_RUNNING_FVAL:
> 
> 
> While building stable rc 5.10 for arm64 the build failed due to
> the following errors / warnings.
> 
> make --silent --keep-going --jobs=8
> O=/home/tuxbuild/.cache/tuxmake/builds/1/tmp ARCH=arm64
> CROSS_COMPILE=aarch64-linux-gnu- 'HOSTCC=sccache clang' 'CC=sccache
> clang'
> drivers/net/ipa/gsi.c:1074:7: error: use of undeclared identifier
> 'GENERIC_EE_CHANNEL_NOT_RUNNING_FVAL'
>         case GENERIC_EE_CHANNEL_NOT_RUNNING_FVAL:
>              ^
> 1 error generated.
> make[4]: *** [scripts/Makefile.build:279: drivers/net/ipa/gsi.o] Error 1
> 
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
> 
> Build log link,
> https://gitlab.com/Linaro/lkft/mirrors/stable/linux-stable-rc/-/jobs/1086862412#L210

I'll go drop this and push out a -rc2 now, thanks.

greg k-h