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SubjectRe: [PATCH v10 09/10] gpio: uniphier: Utilize for_each_set_clump8 macro
On Thu, Mar 14, 2019 at 09:32:37PM +0900, William Breathitt Gray wrote:
> Replace verbose implementation in set_multiple callback with
> for_each_set_clump8 macro to simplify code and improve clarity. An
> improvement in this case is that banks that are not masked will now be
> skipped.
>
> Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
> ---
> drivers/gpio/gpio-uniphier.c | 16 ++++++----------
> 1 file changed, 6 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpio/gpio-uniphier.c b/drivers/gpio/gpio-uniphier.c
> index 0f662b297a95..df640cb29b9c 100644
> --- a/drivers/gpio/gpio-uniphier.c
> +++ b/drivers/gpio/gpio-uniphier.c
> @@ -15,9 +15,6 @@
> #include <linux/spinlock.h>
> #include <dt-bindings/gpio/uniphier-gpio.h>
>
> -#define UNIPHIER_GPIO_BANK_MASK \
> - GENMASK((UNIPHIER_GPIO_LINES_PER_BANK) - 1, 0)
> -
> #define UNIPHIER_GPIO_IRQ_MAX_NUM 24
>
> #define UNIPHIER_GPIO_PORT_DATA 0x0 /* data */
> @@ -147,15 +144,14 @@ static void uniphier_gpio_set(struct gpio_chip *chip,
> static void uniphier_gpio_set_multiple(struct gpio_chip *chip,
> unsigned long *mask, unsigned long *bits)
> {
> - unsigned int bank, shift, bank_mask, bank_bits;
> - int i;
> + unsigned int i;
> + unsigned long bank_mask;
> + unsigned int bank;
> + unsigned int bank_bits;
>
> - for (i = 0; i < chip->ngpio; i += UNIPHIER_GPIO_LINES_PER_BANK) {
> + for_each_set_clump8(i, bank_mask, mask, chip->ngpio) {
> bank = i / UNIPHIER_GPIO_LINES_PER_BANK;
> - shift = i % BITS_PER_LONG;
> - bank_mask = (mask[BIT_WORD(i)] >> shift) &
> - UNIPHIER_GPIO_BANK_MASK;
> - bank_bits = bits[BIT_WORD(i)] >> shift;
> + bank_bits = bitmap_get_value8(bits, chip->ngpio, i);
>
> uniphier_gpio_bank_write(chip, bank, UNIPHIER_GPIO_PORT_DATA,
> bank_mask, bank_bits);
> --
> 2.21.0

Masahiro,

I noticed this loops per GPIO bank and uniphier_gpio_bank_write is
called each time to update the respective bank. The
uniphier_gpio_reg_update function however is calling writel to update
the registers; yet only 8 bits (UNIPHIER_GPIO_LINES_PER_BANK) are
updated at a time via the uniphier_gpio_bank_write call in the
uniphier_gpio_set_multiple function.

Can more than one bank be updated at a time via writel (e.g. 4 banks at
8 bits per bank via a single 32-bit writel call)? If so, instead of
using the for_each_set_clump8 macro, it may be more efficient to loop
through 4 banks at a time.

William Breathitt Gray

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