Re: [PATCH] platform:x86 decouple telemetry driver from the optional IPC resources

[Darren Hart <dvhart@infradead.org>]

On Sun, Apr 10, 2016 at 09:46:48PM +0800, Li, Aubrey wrote:
> On 2016/4/10 21:17, Andy Shevchenko wrote:
> > On Thu, Mar 31, 2016 at 10:28 PM, Aubrey Li <aubrey.li@linux.intel.com> wrote:
> >> Currently the optional IPC resources prevent telemetry driver from
> >> probing if these resources are not in ACPI table. This patch decouples
> >> telemetry driver from these optional resources, so that telemetry driver
> >> has dependency only on the necessary ACPI resources.
> > 
> > Darren, I have comments as well.
> > 
> >>
> >> Signed-off-by: Aubrey Li <aubrey.li@linux.intel.com>
> >> ---
> >>  drivers/platform/x86/intel_pmc_ipc.c   |   48 +++++++++++++++-----------------
> >>  drivers/platform/x86/intel_punit_ipc.c |   48 +++++++++++++++++++++-----------
> >>  2 files changed, 54 insertions(+), 42 deletions(-)
> >>
> >> diff --git a/drivers/platform/x86/intel_pmc_ipc.c b/drivers/platform/x86/intel_pmc_ipc.c
> >> index 092519e..29d9c02 100644
> >> --- a/drivers/platform/x86/intel_pmc_ipc.c
> >> +++ b/drivers/platform/x86/intel_pmc_ipc.c
> >> @@ -686,8 +686,8 @@ static int ipc_plat_get_res(struct platform_device *pdev)
> >>         ipcdev.acpi_io_size = size;
> >>         dev_info(&pdev->dev, "io res: %pR\n", res);
> >>
> >> -       /* This is index 0 to cover BIOS data register */
> >>         punit_res = punit_res_array;
> >> +       /* This is index 0 to cover BIOS data register */
> >>         res = platform_get_resource(pdev, IORESOURCE_MEM,
> >>                                     PLAT_RESOURCE_BIOS_DATA_INDEX);
> >>         if (!res) {
> >> @@ -697,55 +697,51 @@ static int ipc_plat_get_res(struct platform_device *pdev)
> >>         *punit_res = *res;
> >>         dev_info(&pdev->dev, "punit BIOS data res: %pR\n", res);
> >>
> >> +       /* This is index 1 to cover BIOS interface register */
> >>         res = platform_get_resource(pdev, IORESOURCE_MEM,
> >>                                     PLAT_RESOURCE_BIOS_IFACE_INDEX);
> >>         if (!res) {
> >>                 dev_err(&pdev->dev, "Failed to get res of punit BIOS iface\n");
> >>                 return -ENXIO;
> >>         }
> >> -       /* This is index 1 to cover BIOS interface register */
> >>         *++punit_res = *res;
> >>         dev_info(&pdev->dev, "punit BIOS interface res: %pR\n", res);
> >>
> >> +       /* This is index 2 to cover ISP data register, optional */
> > 
> > All above looks like a commentary fixes (except an additional
> > 'optional' word in one case). Can you do this separately?
> 
> I don't think it's necessary.
> 

This is typically necessary as you would not want the comment fixes above to be
backed out if the functional changes below were found to be buggy and reverted.
This is why we encourage small functional changes. It protects against
inadvertent reverts and facilitates review.

That said, these comment changes continue below in a way that makes it a bit
difficult to isolate them out, so I do not particularly object.

That said, everyone should understand that Andy is part of the
platform-driver-x86 maintainer team so please respect his comments as such.

> > 
> > 
> >>         res = platform_get_resource(pdev, IORESOURCE_MEM,
> >>                                     PLAT_RESOURCE_ISP_DATA_INDEX);
> >> -       if (!res) {
> >> -               dev_err(&pdev->dev, "Failed to get res of punit ISP data\n");
> >> -               return -ENXIO;
> >> +       ++punit_res;
> >> +       if (res) {
> >> +               *punit_res = *res;
> >> +               dev_info(&pdev->dev, "punit ISP data res: %pR\n", res);
> > 
> > Okay, what if you re-arrange this to some helper first
> > 
> 
> Thanks for the idea, but I don't like a helper here, did you see
> anything harmful of the current implementation?

In both arguments, we need to identify the WHY.

I imagine Andy is trying to reduce the copy and paste potential for error as
well as error introduction in future patches. There are... 7 or so cases with
near identical usage, that's a compelling argument for a refactor such as the
helper Andy suggests.

Aubrey, you said you don't like it. Why is that? Will it not save enough lines
of code to be worth it? Are you concerned about revalidating the change?

In my opinion, a refactor is a good suggestion, but I would be OK with this
patch as it is and a refactor to follow. I hesitate to do this when the refactor
is really critical as it may not happen, but in this case, it doesn't seem
absolutely necessary.

> 
> > int …_assign_res(*pdev, index, *punit_res)
> > {
> >  struct resource res;
> >  res = platform_get_resource(pdev, …, index);
> >  if (!res)
> >   return -ERRNO;
> >  *punit_res = *res;
> >  dev_dbg(%pR);
> >  return 0;
> > }
> > 
> > In this patch you move to optional by
> > dev_err -> dev_warn
> > 
> > and use
> > 
> > if (ret)
> >   dev_warn( "…skip  optional resource…" );
> > 
> > instead of
> > if (ret) {
> >  dev_err();
> >  return ret;
> > }
> > 
> >>         }
> >> -       /* This is index 2 to cover ISP data register */
> >> -       *++punit_res = *res;
> >> -       dev_info(&pdev->dev, "punit ISP data res: %pR\n", res);
> >>
> >> +       /* This is index 3 to cover ISP interface register, optional */
> >>         res = platform_get_resource(pdev, IORESOURCE_MEM,
> >>                                     PLAT_RESOURCE_ISP_IFACE_INDEX);
> >> -       if (!res) {
> >> -               dev_err(&pdev->dev, "Failed to get res of punit ISP iface\n");
> >> -               return -ENXIO;
> >> +       ++punit_res;
> >> +       if (res) {
> >> +               *punit_res = *res;
> >> +               dev_info(&pdev->dev, "punit ISP interface res: %pR\n", res);
> >>         }
> >> -       /* This is index 3 to cover ISP interface register */
> >> -       *++punit_res = *res;
> >> -       dev_info(&pdev->dev, "punit ISP interface res: %pR\n", res);
> >>
> >> +       /* This is index 4 to cover GTD data register, optional */
> >>         res = platform_get_resource(pdev, IORESOURCE_MEM,
> >>                                     PLAT_RESOURCE_GTD_DATA_INDEX);
> >> -       if (!res) {
> >> -               dev_err(&pdev->dev, "Failed to get res of punit GTD data\n");
> >> -               return -ENXIO;
> >> +       ++punit_res;
> >> +       if (res) {
> >> +               *punit_res = *res;
> >> +               dev_info(&pdev->dev, "punit GTD data res: %pR\n", res);
> >>         }
> >> -       /* This is index 4 to cover GTD data register */
> >> -       *++punit_res = *res;
> >> -       dev_info(&pdev->dev, "punit GTD data res: %pR\n", res);
> >>
> >> +       /* This is index 5 to cover GTD interface register, optional */
> >>         res = platform_get_resource(pdev, IORESOURCE_MEM,
> >>                                     PLAT_RESOURCE_GTD_IFACE_INDEX);
> >> -       if (!res) {
> >> -               dev_err(&pdev->dev, "Failed to get res of punit GTD iface\n");
> >> -               return -ENXIO;
> >> +       ++punit_res;
> >> +       if (res) {
> >> +               *punit_res = *res;
> >> +               dev_info(&pdev->dev, "punit GTD interface res: %pR\n", res);
> >>         }
> >> -       /* This is index 5 to cover GTD interface register */
> >> -       *++punit_res = *res;
> >> -       dev_info(&pdev->dev, "punit GTD interface res: %pR\n", res);
> >>
> >>         res = platform_get_resource(pdev, IORESOURCE_MEM,
> >>                                     PLAT_RESOURCE_IPC_INDEX);
> >> diff --git a/drivers/platform/x86/intel_punit_ipc.c b/drivers/platform/x86/intel_punit_ipc.c
> >> index bd87540..a47a41f 100644
> >> --- a/drivers/platform/x86/intel_punit_ipc.c
> >> +++ b/drivers/platform/x86/intel_punit_ipc.c
> >> @@ -227,6 +227,11 @@ static int intel_punit_get_bars(struct platform_device *pdev)
> >>         struct resource *res;
> >>         void __iomem *addr;
> >>
> >> +       /*
> >> +        * The following resources are required
> >> +        * - BIOS_IPC BASE_DATA
> >> +        * - BIOS_IPC BASE_IFACE
> >> +        */
> >>         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >>         addr = devm_ioremap_resource(&pdev->dev, res);
> >>         if (IS_ERR(addr))
> >> @@ -239,29 +244,40 @@ static int intel_punit_get_bars(struct platform_device *pdev)
> >>                 return PTR_ERR(addr);
> >>         punit_ipcdev->base[BIOS_IPC][BASE_IFACE] = addr;
> >>
> >> +       /*
> >> +        * The following resources are optional
> >> +        * - ISPDRIVER_IPC BASE_DATA
> >> +        * - ISPDRIVER_IPC BASE_IFACE
> >> +        * - GTDRIVER_IPC BASE_DATA
> >> +        * - GTDRIVER_IPC BASE_IFACE
> >> +        */
> >>         res = platform_get_resource(pdev, IORESOURCE_MEM, 2);
> >> -       addr = devm_ioremap_resource(&pdev->dev, res);
> >> -       if (IS_ERR(addr))
> >> -               return PTR_ERR(addr);
> >> -       punit_ipcdev->base[ISPDRIVER_IPC][BASE_DATA] = addr;
> >> +       if (res) {
> >> +               addr = devm_ioremap_resource(&pdev->dev, res);
> >> +               if (!IS_ERR(addr))
> >> +                       punit_ipcdev->base[ISPDRIVER_IPC][BASE_DATA] = addr;
> >> +       }
> > 
> > And here, what about just replacing return to dev_warn()?
> 
> I don't think we need to continue the subsequent ops if an error address
> returns.

Why is that? Will the driver fail to provide any functionality? Or could it be
the other IFACEs could still be of some use?

This one does need a justification.

> 
> Thanks,
> -Aubrey
>