On Wednesday, May 19, 2010 9:00 AM, H Hartley Sweeten wrote:
> On Wednesday, May 19, 2010 8:46 AM, Hennerich, Michael wrote:
>> H Hartley Sweeten wrote on 2010-05-19:
>>> On Wednesday, May 19, 2010 3:01 AM, Michael Hennerich wrote:
>>>> Similar patch as reported by Oskar Schirmer <os@xxxxxxxxx> for the
>>>> AD7877.
>>>>
>>>> With no word size given in the users platform data, a generic spi host
>>>> controller driver will assume a default word size of eight bit. Ensure
>>>> spi->bits_per_word is set for 16-bit transfers.
>>>>
>>>> Signed-off-by: Michael Hennerich <Michael.hennerich@xxxxxxxxxx>
>>>> ---
>>>> drivers/input/touchscreen/ad7879.c | 10 ++++++++++
>>>> 1 files changed, 10 insertions(+), 0 deletions(-)
>>>> diff --git a/drivers/input/touchscreen/ad7879.c
>>>> b/drivers/input/touchscreen/ad7879.c
>>>> index 794d070..ff490c0 100644
>>>> --- a/drivers/input/touchscreen/ad7879.c
>>>> +++ b/drivers/input/touchscreen/ad7879.c
>>>> @@ -715,6 +715,16 @@ static int __devinit ad7879_probe(struct
>>>> spi_device
>>>> *spi)
>>>> return -EINVAL;
>>>> }
>>>> + if (spi->bits_per_word != 16) {
>>>
>>> The master never sets this field so this test isn't needed. The
>>> platform specific spi_board_info "could" set the field but I don't
>>> think any currently do.
Oh.. And I was wrong about the spi_board_info being able to set the field.
>From the struct spi_board_info definition in include/linux/spi/spi.h:
* When adding new SPI devices to the device tree, these structures serve
* as a partial device template. They hold information which can't always
* be determined by drivers. Information that probe() can establish (such
* as the default transfer wordsize) is not included here.
The Blackfin driver is using the controller_data field to pass the extra
information. Also from the struct spi_board_info definition in
include/linux/spi/spi.h:
* @controller_data: Initializes spi_device.controller_data; some
* controllers need hints about hardware setup, e.g. for DMA.
And from arch/blackfin/include/asm/bfin5xx_spi.h:
/* spi_board_info.controller_data for SPI slave devices,
* copied to spi_device.platform_data ... mostly for dma tuning
*/
struct bfin5xx_spi_chip {
u16 ctl_reg;
u8 enable_dma;
u8 bits_per_word;
u8 cs_change_per_word;
u16 cs_chg_udelay; /* Some devices require 16-bit delays */
u32 cs_gpio;
/* Value to send if no TX value is supplied, usually 0x0 or 0xFFFF */
u16 idle_tx_val;
u8 pio_interrupt; /* Enable spi data irq */
};
>>
>> Blackfin does!
>> Originally my assumption was that everyone does it - that's why this
>> haven't been fixed earlier.
>
> Hmm... It appears they do ;-)
>
> But, it's passed as controller_data that would be specific to the Blackfin
> spi master driver.
Regards,
Hartley
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