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Message-ID: <CANiq72kM9bYJ1Q+dbLumjfQLZW223ZTrYEFqfQ2Jv2SAjrD1NA@mail.gmail.com> Date: Wed, 29 Aug 2018 14:03:18 +0200 From: Miguel Ojeda <miguel.ojeda.sandonis@...il.com> To: Janusz Krzysztofik <jmkrzyszt@...il.com> Cc: Linus Walleij <linus.walleij@...aro.org>, Jonathan Corbet <corbet@....net>, Peter Korsgaard <peter.korsgaard@...co.com>, Peter Rosin <peda@...ntia.se>, Ulf Hansson <ulf.hansson@...aro.org>, Andrew Lunn <andrew@...n.ch>, Florian Fainelli <f.fainelli@...il.com>, "David S. Miller" <davem@...emloft.net>, Dominik Brodowski <linux@...inikbrodowski.net>, Kishon Vijay Abraham I <kishon@...com>, Lars-Peter Clausen <lars@...afoo.de>, Michael Hennerich <Michael.Hennerich@...log.com>, Jonathan Cameron <jic23@...nel.org>, Hartmut Knaack <knaack.h@....de>, Peter Meerwald-Stadler <pmeerw@...erw.net>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby <jslaby@...e.com>, linux-gpio@...r.kernel.org, Linux Doc Mailing List <linux-doc@...r.kernel.org>, linux-i2c@...r.kernel.org, linux-mmc@...r.kernel.org, Network Development <netdev@...r.kernel.org>, linux-iio@...r.kernel.org, devel@...verdev.osuosl.org, linux-serial@...r.kernel.org, linux-kernel <linux-kernel@...r.kernel.org>, Willy Tarreau <w@....eu>, Geert Uytterhoeven <geert@...ux-m68k.org> Subject: Re: [RFC RFT PATCH v4 1/4] gpiolib: Pass bitmaps, not integer arrays, to get/set array Hi Janusz, On Tue, Aug 21, 2018 at 1:43 AM, Janusz Krzysztofik <jmkrzyszt@...il.com> wrote: > Most users of get/set array functions iterate consecutive bits of data, > usually a single integer, while or processing array of results obtained > from or building an array of values to be passed to those functions. > Save time wasted on those iterations by changing the functions' API to > accept bitmaps. > > All current users are updated as well. > > More benefits from the change are expected as soon as planned support > for accepting/passing those bitmaps directly from/to respective GPIO > chip callbacks if applicable is implemented. > > Signed-off-by: Janusz Krzysztofik <jmkrzyszt@...il.com> > --- > Documentation/driver-api/gpio/consumer.rst | 22 ++++---- > drivers/auxdisplay/hd44780.c | 52 +++++++++-------- [CC'ing Willy and Geert for hd44780] > diff --git a/drivers/auxdisplay/hd44780.c b/drivers/auxdisplay/hd44780.c > index f1a42f0f1ded..d340473aa142 100644 > --- a/drivers/auxdisplay/hd44780.c > +++ b/drivers/auxdisplay/hd44780.c > @@ -62,20 +62,19 @@ static void hd44780_strobe_gpio(struct hd44780 *hd) > /* write to an LCD panel register in 8 bit GPIO mode */ > static void hd44780_write_gpio8(struct hd44780 *hd, u8 val, unsigned int rs) > { > - int values[10]; /* for DATA[0-7], RS, RW */ > - unsigned int i, n; > + unsigned long value_bitmap[1]; /* for DATA[0-7], RS, RW */ Why [1]? I understand it is because in other cases it may be more than one, but... > + unsigned int n; > > - for (i = 0; i < 8; i++) > - values[PIN_DATA0 + i] = !!(val & BIT(i)); > - values[PIN_CTRL_RS] = rs; > + value_bitmap[0] = val; > + __assign_bit(PIN_CTRL_RS, value_bitmap, rs); > n = 9; > if (hd->pins[PIN_CTRL_RW]) { > - values[PIN_CTRL_RW] = 0; > + __clear_bit(PIN_CTRL_RW, value_bitmap); > n++; > } > > /* Present the data to the port */ > - gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA0], values); > + gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA0], value_bitmap); > > hd44780_strobe_gpio(hd); > } > @@ -83,32 +82,31 @@ static void hd44780_write_gpio8(struct hd44780 *hd, u8 val, unsigned int rs) > /* write to an LCD panel register in 4 bit GPIO mode */ > static void hd44780_write_gpio4(struct hd44780 *hd, u8 val, unsigned int rs) > { > - int values[10]; /* for DATA[0-7], RS, RW, but DATA[0-3] is unused */ > - unsigned int i, n; > + /* for DATA[0-7], RS, RW, but DATA[0-3] is unused */ > + unsigned long value_bitmap[0]; This one is even more strange... :-) > + unsigned int n; > > /* High nibble + RS, RW */ > - for (i = 4; i < 8; i++) > - values[PIN_DATA0 + i] = !!(val & BIT(i)); > - values[PIN_CTRL_RS] = rs; > + value_bitmap[0] = val; > + __assign_bit(PIN_CTRL_RS, value_bitmap, rs); > n = 5; > if (hd->pins[PIN_CTRL_RW]) { > - values[PIN_CTRL_RW] = 0; > + __clear_bit(PIN_CTRL_RW, value_bitmap); > n++; > } > + value_bitmap[0] = value_bitmap[0] >> PIN_DATA4; Maybe >>=? > > /* Present the data to the port */ > - gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], > - &values[PIN_DATA4]); > + gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], value_bitmap); > > hd44780_strobe_gpio(hd); > > /* Low nibble */ > - for (i = 0; i < 4; i++) > - values[PIN_DATA4 + i] = !!(val & BIT(i)); > + value_bitmap[0] &= ~((1 << PIN_DATA4) - 1); > + value_bitmap[0] |= val & ~((1 << PIN_DATA4) - 1); Are you sure this is correct? You are basically doing an or of value_bitmap and val and clearing the low-nibble. > > /* Present the data to the port */ > - gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], > - &values[PIN_DATA4]); > + gpiod_set_array_value_cansleep(n, &hd->pins[PIN_DATA4], value_bitmap); > > hd44780_strobe_gpio(hd); > } Cheers, Miguel
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