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[80.197.57.18]) by smtp.gmail.com with ESMTPSA id u53-v6sm1556413edm.51.2018.09.05.07.36.58 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Sep 2018 07:36:58 -0700 (PDT) From: Ricardo Ribalda Delgado To: David Woodhouse , Brian Norris , Boris Brezillon , Marek Vasut , Richard Weinberger , Zhouyang Jia , linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org (open list) Cc: Ricardo Ribalda Delgado Subject: [PATCH v2 5/8] mtd: maps: gpio-addr-flash: Replace array with an integer Date: Wed, 5 Sep 2018 16:36:40 +0200 Message-Id: <20180905143643.9871-6-ricardo.ribalda@gmail.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180905143643.9871-1-ricardo.ribalda@gmail.com> References: <20180905143643.9871-1-ricardo.ribalda@gmail.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org By replacing the array with an integer we can avoid completely the bit comparison loop if the value has not changed (by far the most common case). Signed-off-by: Ricardo Ribalda Delgado --- drivers/mtd/maps/gpio-addr-flash.c | 31 +++++++++++++++--------------- 1 file changed, 16 insertions(+), 15 deletions(-) diff --git a/drivers/mtd/maps/gpio-addr-flash.c b/drivers/mtd/maps/gpio-addr-flash.c index 22e100f07112..8f5e3dce9be3 100644 --- a/drivers/mtd/maps/gpio-addr-flash.c +++ b/drivers/mtd/maps/gpio-addr-flash.c @@ -43,7 +43,7 @@ struct async_state { struct map_info map; size_t gpio_count; unsigned *gpio_addrs; - int *gpio_values; + unsigned int gpio_values; unsigned int win_order; }; #define gf_map_info_to_state(mi) ((struct async_state *)(mi)->map_priv_1) @@ -55,22 +55,25 @@ struct async_state { * * Rather than call the GPIO framework every time, cache the last-programmed * value. This speeds up sequential accesses (which are by far the most common - * type). We rely on the GPIO framework to treat non-zero value as high so - * that we don't have to normalize the bits. + * type). */ static void gf_set_gpios(struct async_state *state, unsigned long ofs) { - size_t i = 0; - int value; + int i; ofs >>= state->win_order; - do { - value = ofs & (1 << i); - if (state->gpio_values[i] != value) { - gpio_set_value(state->gpio_addrs[i], value); - state->gpio_values[i] = value; - } - } while (++i < state->gpio_count); + + if (ofs == state->gpio_values) + return; + + for (i = 0; i < state->gpio_count; i++) { + if ((ofs & BIT(i)) == (state->gpio_values & BIT(i))) + continue; + + gpio_set_value(state->gpio_addrs[i], !!(ofs & BIT(i))); + } + + state->gpio_values = ofs; } /** @@ -215,7 +218,7 @@ static int gpio_flash_probe(struct platform_device *pdev) if (!memory || !gpios || !gpios->end) return -EINVAL; - arr_size = sizeof(int) * gpios->end; + arr_size = sizeof(state->gpio_addrs[0]) * gpios->end; state = devm_kzalloc(&pdev->dev, sizeof(*state) + arr_size, GFP_KERNEL); if (!state) return -ENOMEM; @@ -226,9 +229,7 @@ static int gpio_flash_probe(struct platform_device *pdev) */ state->gpio_count = gpios->end; state->gpio_addrs = (void *)(unsigned long)gpios->start; - state->gpio_values = (void *)(state + 1); state->win_order = get_bitmask_order(resource_size(memory)) - 1; - memset(state->gpio_values, 0xff, arr_size); state->map.name = DRIVER_NAME; state->map.read = gf_read; -- 2.18.0