| Message ID | e6a13288c45f824ba23ee8d1410cf0bf9c55fe60.1520886945.git.vilhelm.gray@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi William,
I love your patch! Perhaps something to improve:
[auto build test WARNING on linus/master]
[also build test WARNING on v4.16-rc5 next-20180313]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/William-Breathitt-Gray/Implement-get_multiple-for-ACCES-and-PC104-drivers/20180313-202244
config: x86_64-randconfig-x015-201810 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64
Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings
All warnings (new ones prefixed by >>):
drivers//gpio/gpio-pci-idio-16.c: In function 'idio_16_gpio_get_multiple':
>> drivers//gpio/gpio-pci-idio-16.c:147:35: warning: 'port_state' may be used uninitialized in this function [-Wmaybe-uninitialized]
bits[BIT_WORD(i)] |= port_state << bit_word_offset;
~~~~~~~~~~~^~~~~~~~~~~~~~~~~~
vim +/port_state +147 drivers//gpio/gpio-pci-idio-16.c
105
106 static int idio_16_gpio_get_multiple(struct gpio_chip *chip,
107 unsigned long *mask, unsigned long *bits)
108 {
109 struct idio_16_gpio *const idio16gpio = gpiochip_get_data(chip);
110 unsigned int i;
111 const unsigned int gpio_reg_size = 8;
112 unsigned int bit_word_offset;
113 unsigned int bits_mask;
114 const unsigned long reg_mask = GENMASK(gpio_reg_size, 0);
115 unsigned long port_state;
116
117 /* clear bits array to a clean slate */
118 for (i = 0; i < chip->ngpio; i += BITS_PER_LONG)
119 bits[i / BITS_PER_LONG] = 0;
120
121 /* get bits are evaluated a gpio register size at a time */
122 for (i = 0; i < chip->ngpio; i += gpio_reg_size) {
123 bit_word_offset = i % BITS_PER_LONG;
124 bits_mask = mask[BIT_WORD(i)] & (reg_mask << bit_word_offset);
125 if (!bits_mask) {
126 /* no get bits in this register so skip to next one */
127 continue;
128 }
129
130 /* read bits from current gpio register */
131 switch (i / gpio_reg_size) {
132 case 0:
133 port_state = ioread8(&idio16gpio->reg->out0_7);
134 break;
135 case 1:
136 port_state = ioread8(&idio16gpio->reg->out8_15);
137 break;
138 case 2:
139 port_state = ioread8(&idio16gpio->reg->in0_7);
140 break;
141 case 3:
142 port_state = ioread8(&idio16gpio->reg->in8_15);
143 break;
144 }
145
146 /* store acquired bits */
> 147 bits[BIT_WORD(i)] |= port_state << bit_word_offset;
148 }
149
150 return 0;
151 }
152
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
On Mon, Mar 12, 2018 at 10:49 PM, William Breathitt Gray <vilhelm.gray@gmail.com> wrote: > +static int idio_16_gpio_get_multiple(struct gpio_chip *chip, > + unsigned long *mask, unsigned long *bits) > +{ > + /* clear bits array to a clean slate */ > + for (i = 0; i < chip->ngpio; i += BITS_PER_LONG) > + bits[i / BITS_PER_LONG] = 0; bitmap_clear() or bitmap_zero() > + /* get bits are evaluated a gpio register size at a time */ > + for (i = 0; i < chip->ngpio; i += gpio_reg_size) { > + bit_word_offset = i % BITS_PER_LONG; > + bits_mask = mask[BIT_WORD(i)] & (reg_mask << bit_word_offset); > + if (!bits_mask) { > + /* no get bits in this register so skip to next one */ > + continue; > + } for_each_set_bit() ? > + /* store acquired bits */ > + bits[BIT_WORD(i)] |= port_state << bit_word_offset; __set_bit() __clear_bit() We have bitmap API for *ages*. Is it too hard to check?
On Tue, Mar 13, 2018 at 06:04:33PM +0200, Andy Shevchenko wrote: >On Mon, Mar 12, 2018 at 10:49 PM, William Breathitt Gray ><vilhelm.gray@gmail.com> wrote: > >> +static int idio_16_gpio_get_multiple(struct gpio_chip *chip, >> + unsigned long *mask, unsigned long *bits) >> +{ > > >> + /* clear bits array to a clean slate */ >> + for (i = 0; i < chip->ngpio; i += BITS_PER_LONG) >> + bits[i / BITS_PER_LONG] = 0; > >bitmap_clear() or bitmap_zero() bitmap_zero() would be perfect for this situation. I'll submit a version 2 of this patchset with this change for the various drivers herein. > >> + /* get bits are evaluated a gpio register size at a time */ >> + for (i = 0; i < chip->ngpio; i += gpio_reg_size) { >> + bit_word_offset = i % BITS_PER_LONG; >> + bits_mask = mask[BIT_WORD(i)] & (reg_mask << bit_word_offset); >> + if (!bits_mask) { >> + /* no get bits in this register so skip to next one */ >> + continue; >> + } > >for_each_set_bit() ? > >> + /* store acquired bits */ >> + bits[BIT_WORD(i)] |= port_state << bit_word_offset; > >__set_bit() >__clear_bit() I'm not sure for_each_set_bit() and __set_bit()/__clear_bit() would be good for this particular situation since I'm working with the entire register word (8 bits for this specific device) at a time. Since I know each register word is 8-bits, I can make 8-bit jumps and skips rather than evaluating each bit individually. Similarly, it seems more efficient to store the input 8 bits at a time rather than breaking it up to individual bits. However, I do see how all these inline bitwise operations could make it difficult to follow the code, so perhaps I can break it up across more lines so that the logic of the loop becomes easier to read. William Breathitt Gray > >We have bitmap API for *ages*. Is it too hard to check? > >-- >With Best Regards, >Andy Shevchenko -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/gpio/gpio-pci-idio-16.c b/drivers/gpio/gpio-pci-idio-16.c index 57d1b7fbf07b..8c5ec301c7ff 100644 --- a/drivers/gpio/gpio-pci-idio-16.c +++ b/drivers/gpio/gpio-pci-idio-16.c @@ -103,6 +103,53 @@ static int idio_16_gpio_get(struct gpio_chip *chip, unsigned int offset) return !!(ioread8(&idio16gpio->reg->in8_15) & (mask >> 24)); } +static int idio_16_gpio_get_multiple(struct gpio_chip *chip, + unsigned long *mask, unsigned long *bits) +{ + struct idio_16_gpio *const idio16gpio = gpiochip_get_data(chip); + unsigned int i; + const unsigned int gpio_reg_size = 8; + unsigned int bit_word_offset; + unsigned int bits_mask; + const unsigned long reg_mask = GENMASK(gpio_reg_size, 0); + unsigned long port_state; + + /* clear bits array to a clean slate */ + for (i = 0; i < chip->ngpio; i += BITS_PER_LONG) + bits[i / BITS_PER_LONG] = 0; + + /* get bits are evaluated a gpio register size at a time */ + for (i = 0; i < chip->ngpio; i += gpio_reg_size) { + bit_word_offset = i % BITS_PER_LONG; + bits_mask = mask[BIT_WORD(i)] & (reg_mask << bit_word_offset); + if (!bits_mask) { + /* no get bits in this register so skip to next one */ + continue; + } + + /* read bits from current gpio register */ + switch (i / gpio_reg_size) { + case 0: + port_state = ioread8(&idio16gpio->reg->out0_7); + break; + case 1: + port_state = ioread8(&idio16gpio->reg->out8_15); + break; + case 2: + port_state = ioread8(&idio16gpio->reg->in0_7); + break; + case 3: + port_state = ioread8(&idio16gpio->reg->in8_15); + break; + } + + /* store acquired bits */ + bits[BIT_WORD(i)] |= port_state << bit_word_offset; + } + + return 0; +} + static void idio_16_gpio_set(struct gpio_chip *chip, unsigned int offset, int value) { @@ -299,6 +346,7 @@ static int idio_16_probe(struct pci_dev *pdev, const struct pci_device_id *id) idio16gpio->chip.direction_input = idio_16_gpio_direction_input; idio16gpio->chip.direction_output = idio_16_gpio_direction_output; idio16gpio->chip.get = idio_16_gpio_get; + idio16gpio->chip.get_multiple = idio_16_gpio_get_multiple; idio16gpio->chip.set = idio_16_gpio_set; idio16gpio->chip.set_multiple = idio_16_gpio_set_multiple;
The ACCES I/O PCI-IDIO-16 series of devices provides 16 optically-isolated digital inputs accessed via two 8-bit ports. Since eight input lines are acquired on a single port input read, the PCI-IDIO-16 GPIO driver may improve multiple input reads by utilizing a get_multiple callback. This patch implements the idio_16_gpio_get_multiple function which serves as the respective get_multiple callback. Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com> --- drivers/gpio/gpio-pci-idio-16.c | 48 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+)