On Mon, Feb 8, 2016 at 5:14 PM, Mika Westerberg
<mika.westerberg@xxxxxxxxxxxxxxx> wrote:
> It turns out that in Windows SPI drivers are responsible for handling ACPI
> DeviceSelection field themselves. Furthermore there has been separate
> drivers for big core and atom SPI host controllers. For atom (including
> Baytrail and Braswell) the driver starts DeviceSelection from 1 instead of 0
> as expected by the Linux SPI core.
>
> As an example Microsoft Surface 3 has touch screen connected to SPI bus
> described in ACPI DSDT like this:
>
> Scope (_SB.PCI0.SPI1)
> {
> Device (NTRG)
> {
> Name (_HID, "MSHW0037") // _HID: Hardware ID
> ...
> Name (CRS1, ResourceTemplate ()
> {
> SpiSerialBus (0x0001, // SPI DeviceSelection
> PolarityLow, FourWireMode, 0x10,
> ControllerInitiated, 0x007A1200, ClockPolarityLow,
> ClockPhaseFirst, "\\_SB.PCI0.SPI1",
> 0x00, ResourceConsumer, ,
> )
>
> This fails to enumerate because ACPI DeviceSelection of 1 is greater than
> number of chip selects the driver supports [1].
>
> This series adds a new hook to struct spi_master ->fw_translate_cs() that
> allows a driver to translate the chip select number from firmware to the
> numbering scheme expected by the Linux SPI core and implement that for both
> Baytrail and Braswell.
>
> In addition to that we add support for the second chip select found on
> Braswell.
>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
> This is a second revision of the series. Changes to the v1:
>
> - Added Jarkko's Reviewed-by
> - Use runtime ACPI check in pxa2xx_spi_fw_translate_cs() to prevent build
> breakage found by kbuild test robot.
>
> [1] https://bugzilla.kernel.org/show_bug.cgi?id=104291
>
> Mika Westerberg (4):
> spi: Let drivers translate ACPI DeviceSelection to suitable Linux chip select
> spi: pxa2xx: Translate ACPI DeviceSelection to Linux chip select on Baytrail
> spi: pxa2xx: Move chip select control bits into lpss_config structure
> spi: pxa2xx: Add support for both chip selects on Intel Braswell
>
> drivers/spi/spi-pxa2xx.c | 108 ++++++++++++++++++++++++++++++++++-----------
> drivers/spi/spi.c | 19 +++++++-
> include/linux/pxa2xx_ssp.h | 1 +
> include/linux/spi/spi.h | 5 +++
> 4 files changed, 107 insertions(+), 26 deletions(-)
>
> --
> 2.7.0
>
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--
With Best Regards,
Andy Shevchenko
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