Re: [PATCH v2 4/4] spi: Use Apple device properties in absence of ACPI resources

[Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>]

On Wed, Jun 28, 2017 at 07:20:19PM +0200, Lukas Wunner wrote:
> MacBooks and MacBook Pros introduced since 2015 return empty _CRS data
> for SPI slaves, causing device initialization to fail.  Most of the
> information that would normally be conveyed via _CRS is available
> through ACPI device properties instead, so take advantage of them.
> 
> The meaning and appropriate usage of the device properties was reverse
> engineered by Ronald Tschalär and carried over from these commits
> authored by him:
> 
> https://github.com/cb22/macbook12-spi-driver/commit/9a416d699ef4
> https://github.com/cb22/macbook12-spi-driver/commit/0c34936ed9a1
> 
> According to Ronald, the device properties have the following meaning:
> 
> spiSclkPeriod   /* period in ns */
> spiWordSize     /* in number of bits */
> spiBitOrder     /* 1 = MSB_FIRST, 0 = LSB_FIRST */
> spiSPO          /* clock polarity: 0 = low, 1 = high */
> spiSPH          /* clock phase: 0 = first, 1 = second */
> spiCSDelay      /* delay between cs and receive on reads in 10 us */
> resetA2RUsec    /* active-to-receive delay? */
> resetRecUsec    /* receive delay? */
> 
> Cc: Mark Brown <broonie@xxxxxxxxxx>
> Cc: Federico Lorenzi <florenzi@xxxxxxxxx>
> Reported-by: Leif Liddy <leif.liddy@xxxxxxxxx>
> Tested-by: Ronald Tschalär <ronald@xxxxxxxxxxxxx>
> Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>

Acked-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
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