From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [PATCH] mmc: sdhci-pci: Try "cd" for card-detect lookup before using NULL Date: Mon, 29 Oct 2018 19:43:56 +0200 Message-ID: <20181029174356.GR10650@smile.fi.intel.com> References: <20181018215101.169847-1-rajatja@google.com> <20181024100230.GQ10650@smile.fi.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Rajat Jain Cc: Dmitry Torokhov , "Hunter, Adrian" , Ulf Hansson , linux-mmc@vger.kernel.org, Linus Walleij , Rajat Jain , Linux Kernel Mailing List , Mika Westerberg , linux-gpio@vger.kernel.org, linux-acpi@vger.kernel.org List-Id: linux-mmc@vger.kernel.org On Mon, Oct 29, 2018 at 10:22:02AM -0700, Rajat Jain wrote: > On Mon, Oct 29, 2018 at 8:23 AM Andy Shevchenko > wrote: > > On Wed, Oct 24, 2018 at 9:03 PM Dmitry Torokhov wrote: > > > On Wed, Oct 24, 2018 at 3:02 AM Andy Shevchenko > > > 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 > > > > > 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. -- With Best Regards, Andy Shevchenko