linux-kernel - Re: [PATCH 1/2] platform/x86: i2c-multi-instantiate: Add flag for passing fwnode

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Date:   Sun, 26 Apr 2020 20:59:14 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Hans de Goede <hdegoede@...hat.com>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] platform/x86: i2c-multi-instantiate: Add flag for
 passing fwnode

On Sun, Apr 26, 2020 at 1:47 PM Hans de Goede <hdegoede@...hat.com> wrote:
>
> In some cases the driver for the i2c_client-s which i2c-multi-instantiate
> instantiates may need access some fields / methods from to the ACPI fwnode
> for which i2c_clients are being instantiated.
>
> An example of this are CPLM3218 ACPI device-s. These contain CPM0 and
> CPM1 packages with various information (e.g. register init values) which
> the driver needs.
>
> Passing the fwnode through the i2c_board_info struct also gives the
> i2c-core access to it, and if we do not pass an IRQ then the i2c-core
> will use the fwnode to get an IRQ, see i2c_acpi_get_irq().

I'm wondering, can we rather do it in the same way like we do for
GPIO/APIC case here.
Introduce IRQ_RESOURCE_SHARED (or so) and

case _SHARED:
 irq = i2c_acpi_get_irq();
...

?

>
> This is a problem when there is only an IRQ for 1 of the clients described
> in the ACPI device we are instantiating clients for. If we unconditionally
> pass the fwnode, then i2c_acpi_get_irq() will assign the same IRQ to all
> clients instantiated, leading to kernel-oopses like this (BSG1160 device):
>
> [   27.340557] genirq: Flags mismatch irq 76. 00002001 (bmc150_magn_event) vs. 00000001 (bmc150_accel_event)
> [   27.340567] Call Trace:
> ...
>
> So we cannot simply always pass the fwnode. This commit adds a PASS_FWNODE
> flag, which can be used to pass the fwnode in cases where we do not have
> the IRQ problem and the driver for the instantiated client(s) needs access
> to the fwnode.
>
> Signed-off-by: Hans de Goede <hdegoede@...hat.com>
> ---
>  drivers/platform/x86/i2c-multi-instantiate.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/platform/x86/i2c-multi-instantiate.c b/drivers/platform/x86/i2c-multi-instantiate.c
> index 6acc8457866e..dcafb1a29d17 100644
> --- a/drivers/platform/x86/i2c-multi-instantiate.c
> +++ b/drivers/platform/x86/i2c-multi-instantiate.c
> @@ -20,6 +20,8 @@
>  #define IRQ_RESOURCE_GPIO      1
>  #define IRQ_RESOURCE_APIC      2
>
> +#define PASS_FWNODE            BIT(2)
> +
>  struct i2c_inst_data {
>         const char *type;
>         unsigned int flags;
> @@ -93,6 +95,10 @@ static int i2c_multi_inst_probe(struct platform_device *pdev)
>                 snprintf(name, sizeof(name), "%s-%s.%d", dev_name(dev),
>                          inst_data[i].type, i);
>                 board_info.dev_name = name;
> +
> +               if (inst_data[i].flags & PASS_FWNODE)
> +                       board_info.fwnode = dev->fwnode;
> +
>                 switch (inst_data[i].flags & IRQ_RESOURCE_TYPE) {
>                 case IRQ_RESOURCE_GPIO:
>                         ret = acpi_dev_gpio_irq_get(adev, inst_data[i].irq_idx);
> --
> 2.26.0
>


-- 
With Best Regards,
Andy Shevchenko