From: Rajat Jain <rajatxjain@gmail.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Rajat Jain <rajatja@google.com>,
Dmitry Torokhov <dtor@google.com>,
"Hunter, Adrian" <adrian.hunter@intel.com>,
Ulf Hansson <ulf.hansson@linaro.org>,
linux-mmc@vger.kernel.org,
Linus Walleij <linus.walleij@linaro.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
linux-gpio@vger.kernel.org, linux-acpi@vger.kernel.org
Subject: Re: [PATCH] mmc: sdhci-pci: Try "cd" for card-detect lookup before using NULL
Date: Mon, 29 Oct 2018 12:43:24 -0700 [thread overview]
Message-ID: <CAA93t1oaZ5zkv+BsGnYZg6pqKv0DzXi3j8oZHUyTyffUWHtHug@mail.gmail.com> (raw)
In-Reply-To: <20181029174356.GR10650@smile.fi.intel.com>
On Mon, Oct 29, 2018 at 10:44 AM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Mon, Oct 29, 2018 at 10:22:02AM -0700, Rajat Jain wrote:
> > On Mon, Oct 29, 2018 at 8:23 AM Andy Shevchenko
> > <andy.shevchenko@gmail.com> wrote:
> > > On Wed, Oct 24, 2018 at 9:03 PM Dmitry Torokhov <dtor@google.com> wrote:
> > > > On Wed, Oct 24, 2018 at 3:02 AM Andy Shevchenko
> > > > <andy.shevchenko@gmail.com> wrote:
> > > > > On Mon, Oct 22, 2018 at 04:34:55PM -0700, Rajat Jain wrote:
> > > > > > On Fri, Oct 19, 2018 at 2:13 AM Andy Shevchenko
> > > > > > <andy.shevchenko@gmail.com> wrote:
>
> > > > > > Also, the driver may not
> > > > > > really know?
> > > > >
> > > > > I think in such case the bug in HW design and / or driver.
> > > >
> > > > Why? You can have a shared or dedicated interrupt and the driver does
> > > > not really need to know if it can poll the status.
> > >
> > > Yes, that's my point either we get 1:1 mapping between slot and GPIOs
> > > or have a possibility to read back from some register(s) the actual
> > > status of all of them, otherwise it's a bad design.
> >
> > No, AFAIU, the driver only should only be able to read the status of
> > *the* interrupt that was fired? (as opposite to the ability to read
> > *all of them* when an interrupt fires).
>
> I can't be sure in the details of this (sdhci) driver, I'm not a maintainer of
> that one. So, my above conclusions are purely generic.
>
> > > > > > 2) I'm not really sure what should I set "active_low" to? Isn't this
> > > > > > something that should be specified by platform / ACPI too, and driver
> > > > > > should just be able to say say choose whatever the ACPI says?
> > > > > >
> > > > > > struct acpi_gpio_params {
> > > > > > unsigned int crs_entry_index;
> > > > > > unsigned int line_index;
> > > > > > bool active_low;
> > > > > > };
>
>
> > > > > ACPI specification misses this property, that's why we have it in the
> > > > > structure. In your case it should be provided by _DSD and thus be consistent
> > > > > with the hardcoded values.
> > > >
> > > > Again, you think as if the driver was platform specific; it is not. I
> > > > have 1000s of systems with different ACPI tables. Let's say half of
> > > > them use one polarity, and half another. Which polarity do you propose
> > > > to use?
> > >
> > > Use one table for one half and another for the rest.
> >
> > But how does driver determine which table to use for which platform?
> > (Currently the driver is platform independent).
>
> Based on vendor and device IDs in any form of it.
The vendor ID and device ID here would mean building a table of
platforms ids in this (currently platform independent) driver. I'm not
sure if my original patch introduces any problems that are worth
solving using such a table.
I would thus prefer to solve it using my original patch, I would
respin it taking care of your other review comments.
Thanks and best regards,
Rajat
>
> --
> With Best Regards,
> Andy Shevchenko
>
>
next prev parent reply other threads:[~2018-10-29 19:43 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-25 20:54 sdhci driver card-detect is broken because gpiolib can't fallback to _CRS? Rajat Jain
2018-09-26 7:47 ` Mika Westerberg
2018-09-26 8:42 ` Andy Shevchenko
2018-09-26 19:25 ` Rajat Jain
2018-09-27 7:26 ` Andy Shevchenko
2018-09-27 17:56 ` Rajat Jain
2018-09-28 8:42 ` Linus Walleij
2018-09-28 12:34 ` Rajat Jain
2018-09-28 13:13 ` Linus Walleij
2018-10-18 21:51 ` [PATCH] mmc: sdhci-pci: Try "cd" for card-detect lookup before using NULL Rajat Jain
2018-10-19 9:13 ` Andy Shevchenko
2018-10-22 23:34 ` Rajat Jain
2018-10-24 10:02 ` Andy Shevchenko
2018-10-24 18:03 ` Dmitry Torokhov
2018-10-29 15:23 ` Andy Shevchenko
2018-10-29 17:22 ` Rajat Jain
2018-10-29 17:43 ` Andy Shevchenko
2018-10-29 19:43 ` Rajat Jain [this message]
2018-10-29 22:17 ` [PATCH v2] " Rajat Jain
2018-10-30 7:53 ` Adrian Hunter
2018-11-12 11:05 ` Ulf Hansson
2018-11-12 11:25 ` Andy Shevchenko
2018-11-13 1:26 ` Rajat Jain
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