From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Rajat Jain <rajatja@google.com>
Cc: "Hunter, Adrian" <adrian.hunter@intel.com>,
Ulf Hansson <ulf.hansson@linaro.org>,
linux-mmc@vger.kernel.org,
Linus Walleij <linus.walleij@linaro.org>,
Rajat Jain <rajatxjain@gmail.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Dmitry Torokhov <dtor@google.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: Wed, 24 Oct 2018 13:02:30 +0300 [thread overview]
Message-ID: <20181024100230.GQ10650@smile.fi.intel.com> (raw)
In-Reply-To: <CACK8Z6HOsUcPFyf-GguxPxh_Zdj6gCXP=FpGw-vQXJfnM=cquw@mail.gmail.com>
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:
> > On Fri, Oct 19, 2018 at 12:53 AM Rajat Jain <rajatja@google.com> wrote:
> > > across other users of this API (other MMC host controller drivers).
> >
> > > if (slot->cd_idx >= 0) {
> > > - ret = mmc_gpiod_request_cd(host->mmc, NULL, slot->cd_idx,
> > > + ret = mmc_gpiod_request_cd(host->mmc, "cd", slot->cd_idx,
> > > slot->cd_override_level, 0, NULL);
> >
> > Yes.
> >
> > > + if (ret && ret != -EPROBE_DEFER)
> > > + ret = mmc_gpiod_request_cd(host->mmc, NULL,
> > > + slot->cd_idx,
> > > + slot->cd_override_level,
> > > + 0, NULL);
> >
> > And no. Instead of this part you need to provide an ACPI GPIO mapping table.
>
> Sure, I am willing to do so, and I tried earlier too. However, certain
> doubts arose in my mind when I tried that and I posted my questions
> earlier (https://lkml.org/lkml/2018/9/28/507) but couldn't elicit any
> response. Unfortunately I still do not have answers. My primary
> questions are:
>
> 1) - It seems that 1 SDHCI device may support multiple slots (looking
> at the code). It is not clear to me if they could share card detect
> interrupts, or should have separate ones?
This is more likely question to HW engineers of your platform with a caveat
that there should be a way to distinguish exact slot in which card is being
inserted.
> Also, the driver may not
> really know?
I think in such case the bug in HW design and / or driver.
> So should I add 1 or two pins using the
> devm_acpi_dev_add_driver_gpios().
This depends on the above, e.g. HW design, ACPI tables.
> Is some one familiar with SDHC
> driver can answer these questions, it shall be great.
Actually above questions better to ask in linux-mmc mailing list, which by the
fact is in Cc list already. So, wait for someone to clarify.
> 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.
> Since I do not understand the above two issues, and thus I chose the
> safest path and not disturb the current code so as not to cause any
> regressions.
As far as I can see in the above it is disturbing the current code more than
needed.
>
> Please let me know, and I'm happy to re-spin my patch.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2018-10-24 10:02 UTC|newest]
Thread overview: 24+ 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
2018-09-25 20:54 ` 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 [this message]
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
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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