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Revision bd8733738c5af6114dd15d340b3f8713e9b624c2 authored by Boris Brezillon on 08 February 2015, 18:23:42 UTC, committed by Linus Walleij on 18 March 2015, 01:01:36 UTC 
pinctrl: at91: move lock/unlock_as_irq calls into request/release
 
The gpiochip_lock_as_irq call can fail and return an error,
while the irq_startup is not expected to fail (returns an
unsigned int which is not checked by irq core code).

irq_request/release_resources functions have been created
to address this problem.

Move gpiochip_lock/unlock_as_irq calls into
irq_request/release_resources functions to prevent using a
gpio as an irq if the gpiochip_lock_as_irq call failed.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
1 parent 549e783
Raw File
bfin-spi-notes.txt 
SPI Chip Select behavior:

With the Blackfin on-chip SPI peripheral, there is some logic tied to the CPHA
bit whether the Slave Select Line is controlled by hardware (CPHA=0) or
controlled by software (CPHA=1). However, the Linux SPI bus driver assumes that
the Slave Select is always under software control and being asserted during
the entire SPI transfer. - And not just bits_per_word duration.

In most cases you can utilize SPI MODE_3 instead of MODE_0 to work-around this
behavior. If your SPI slave device in question requires SPI MODE_0 or MODE_2
timing, you can utilize the GPIO controlled SPI Slave Select option instead.
In this case, you should use GPIO based CS for all of your slaves and not just
the ones using mode 0 or 2 in order to guarantee correct CS toggling behavior.

You can even use the same pin whose peripheral role is a SSEL,
but use it as a GPIO instead.
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