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    SubjectRe: [PATCH v7 4/4] gpiolib: Implement fast processing path in get/set array
    Date
    On Thursday, September 20, 2018 5:48:22 PM CEST Janusz Krzysztofik wrote:
    > On Thursday, September 20, 2018 12:11:48 PM CEST Marek Szyprowski wrote:
    > > Hi All,
    > >
    > > On 2018-09-02 14:01, Janusz Krzysztofik wrote:
    > > > Certain GPIO descriptor arrays returned by gpio_get_array() may contain
    > > > information on direct mapping of array members to pins of a single GPIO
    > > > chip in hardware order. In such cases, bitmaps of values can be passed
    > > > directly from/to the chip's .get/set_multiple() callbacks without
    > > > wasting time on iterations.
    > > >
    > > > Add respective code to gpiod_get/set_array_bitmap_complex() functions.
    > > > Pins not applicable for fast path are processed as before, skipping
    > > > over the 'fast' ones.
    > > >
    > > > Cc: Jonathan Corbet <corbet@lwn.net>
    > > > Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
    > >
    > > I've just noticed that this patch landed in today's linux-next. Sadly it
    > > breaks booting of Exynos5250-based Samsung Snow Chromebook (ARM 32bit,
    > > device-tree source arch/arm/boot/dts/exynos5250-snow.dts).
    > >
    > > Booting hangs after detecting MMC cards. Reverting this patch fixes the
    > > boot. I will try later to add some debugs and investigate it further what
    > > really happens when booting hangs.
    >
    > Hi Marek,
    >
    > Thanks for reporting. Could you please try the following fix?

    Hi again,

    I realized the patch was not correct, j, not i, should be updated in second
    hunk. Please try the following one.

    Thanks,
    Janusz

    From a919c504850f6cb40e8e81267a3a37537f7c4fd4 Mon Sep 17 00:00:00 2001
    From: Janusz Krzysztofik <jmkrzyszt@gmail.com>
    Date: Thu, 20 Sep 2018 17:37:21 +0200
    Subject: [PATCH] gpiolib: Fix bitmap index not updated

    While skipping fast path bits, bitmap index is not updated with next
    found zero bit position. Fix it.

    Signed-off-by: Janusz Krzysztofik <jmkrzyszt@gmail.com>
    ---
    drivers/gpio/gpiolib.c | 7 ++++---
    1 file changed, 4 insertions(+), 3 deletions(-)

    diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
    index a53d17745d21..369bdd358fcc 100644
    --- a/drivers/gpio/gpiolib.c
    +++ b/drivers/gpio/gpiolib.c
    @@ -2880,7 +2880,7 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep,
    __set_bit(hwgpio, mask);

    if (array_info)
    - find_next_zero_bit(array_info->get_mask,
    + i = find_next_zero_bit(array_info->get_mask,
    array_size, i);
    else
    i++;
    @@ -2905,7 +2905,8 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep,
    trace_gpio_value(desc_to_gpio(desc), 1, value);

    if (array_info)
    - find_next_zero_bit(array_info->get_mask, i, j);
    + j = find_next_zero_bit(array_info->get_mask, i,
    + j);
    else
    j++;
    }
    @@ -3192,7 +3193,7 @@ int gpiod_set_array_value_complex(bool raw, bool can_sleep,
    }

    if (array_info)
    - find_next_zero_bit(array_info->set_mask,
    + i = find_next_zero_bit(array_info->set_mask,
    array_size, i);
    else
    i++;
    --
    2.16.4



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