On 2/10/15, 23:07, "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx> wrote: >On Tuesday, February 10, 2015 11:59:32 AM Mika Westerberg wrote: >> On Mon, Feb 09, 2015 at 09:02:11PM +0000, Suthikulpanit, Suravee wrote: >> > On 2/9/15, 19:15, "Mika Westerberg" <mika.westerberg@xxxxxxxxxxxxxxx> >> > wrote: >> > >> > >On Mon, Feb 09, 2015 at 12:02:43AM +0100, Rafael J. Wysocki wrote: >> > >> On Monday, February 09, 2015 12:20:03 AM Suravee Suthikulpanit >>wrote: >> > >> > Device drivers typically use ACPI _HIDs/_CIDs listed in struct >> > >>device_driver >> > >> > acpi_match_table to match devices. However, for generic drivers, >>we do >> > >> > not want to list _HID for all supported devices, and some device >> > >>classes >> > >> > do not have _CID (e.g. SATA, USB). Instead, we can leverage ACPI >>_CLS, >> > >> > which specifies PCI-defined class code (i.e. base-class, >>subclass and >> > >> > programming interface). >> > >> > >> > >> > This patch adds support for matching ACPI devices using the _CLS >> > >>method. >> > >> > >> > >> > Signed-off-by: Suravee Suthikulpanit >><Suravee.Suthikulpanit@xxxxxxx> >> > >> >> > >> Greg, Mika, any problems with this? >> > > >> > >Is there some specific reason why this cannot be done in similar way >> > >than PCI already does? >> > > >> > >In other words, stuff _CLS fields to struct acpi_device_id and make >> > >match functions match against those if they are != 0. >> > >> > That was my original thought. Then I realized that the acpi_device_id >>is >> > used >> > to create the device matching table, in which could contain several >> > _HID/_CID. >> > However, most of the added _CLS field would likely ended up being >>unused >> > and >> > taking up space. >> >> Well, PCI is doing that already :) >> >> > In contrast to _HID/_CID, a driver is likely to match just a single >>_CLS. >> > So, I think it is cleaner to have just a dedicate struct >>acpi_device_cls, >> > and >> > a matching function for it. >> >> IMHO cleaner version is the one following PCI. > >I agree. Ok, let me reimplement this part to put "u32 cls" in the struct acpi_device_id, and use that for matching then. > >> Besides, how do you support modules with this? Or did I miss something? > >Good question. Ah. I didn¹t think about this part earlier. IIUC, the current ACPI driver would create modules.alias entry with format: acpi:<HID>:<CID> What do you think if we append the _CLS of the device using the following format: acpi:<HID>:<CID>:<CLS> In case of PCI_CLASS_STORAGE_SATA_AHCI, this would become: acpi:::0x10601 Thanks, Suravee -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
