On Tuesday, August 7, 2018 7:14:20 PM CEST Boris Brezillon wrote:

On Tue,  7 Aug 2018 00:29:15 +0200
Janusz Krzysztofik [off-list ref] wrote:

quoted

Certain GPIO array lookup results may map directly to GPIO pins of a
single GPIO chip in hardware order.  If that condition is recognized
and handled efficiently, significant performance gain of get/set array
functions may be possible.

While processing a request for an array of GPIO descriptors, verify if
the descriptors just collected represent consecutive pins of a single
GPIO chip.  Pass that information with the array to the caller so it
can benefit from enhanced performance as soon as bitmap based get/set
array functions which can make efficient use of that are available.

Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
---
 Documentation/driver-api/gpio/consumer.rst |  4 +++-
 drivers/gpio/gpiolib.c                     | 14 ++++++++++++++
 include/linux/gpio/consumer.h              |  1 +
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/Documentation/driver-api/gpio/consumer.rst b/Documentation/driver-api/gpio/consumer.rst
index aa03f389d41d..38a990b5f3b6 100644
--- a/Documentation/driver-api/gpio/consumer.rst
+++ b/Documentation/driver-api/gpio/consumer.rst

@@ -109,11 +109,13 @@ For a function using multiple GPIOs all of those can be obtained with one call::
 					   enum gpiod_flags flags)
 
 This function returns a struct gpio_descs which contains an array of
-descriptors::
+descriptors.  It may also contain a valid descriptor of a single GPIO chip in
+case the array strictly matches pin hardware layout of the chip::
 
 	struct gpio_descs {
 		unsigned int ndescs;
 		struct gpio_desc *desc[];
+		struct gpio_chip *chip;

chip is placed at the beginning of the struct in the real code, which
is expected since putting it at the end won't work because of the
desc[] declaration.

Yes, I've already noticed that and will fix on next iteration, thanks.

Janusz