| From | Linus Walleij <> | Date | Tue, 7 Aug 2018 01:29:43 +0200 | Subject | Re: [RFC PATCH v2 09/12] gpiolib: Identify GPIO descriptor arrays with direct mapping |
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Hi Janusz!
On Tue, Aug 7, 2018 at 12:29 AM Janusz Krzysztofik <jmkrzyszt@gmail.com> wrote:
> 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> (...) > 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;
This must be motivated: if the only purpose is to indicate to the consumer that all GPIOs are on the same chip, why not just have a
bool all_on_same_chip;
That you set to true if these are all on the same chip?
Yours, Linus Walleij
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