From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Andrew Cooks <andrew.cooks@opengear.com>
Cc: Linus Walleij <linus.walleij@linaro.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
platypus-sw@opengear.com
Subject: Re: [PATCH] gpio-pca953x: fall back to byte-at-a-time for 24-bit io
Date: Fri, 29 Dec 2017 11:44:47 +0200 [thread overview]
Message-ID: <CAHp75Vcpdh36yjXCCOQthYKdY3vPi5EDrqFWauyv9WDgjcZPYQ@mail.gmail.com> (raw)
In-Reply-To: <1512440242-8983-1-git-send-email-andrew.cooks@opengear.com>
On Tue, Dec 5, 2017 at 4:17 AM, Andrew Cooks <andrew.cooks@opengear.com> wrote:
> Using TCA6424A with i2c-piix4 bus driver requires byte-at-a-time IO,
> because the i2c-piix4 driver (and probably some SMBus controllers) don't
> support I2C_SMBUS_I2C_BLOCK_DATA.
Why not to fix piix4 for now?
> static int pca953x_write_regs_24(struct pca953x_chip *chip, int reg, u8 *val)
> {
> + int ret, i;
> int bank_shift = fls((chip->gpio_chip.ngpio - 1) / BANK_SZ);
>
> - return i2c_smbus_write_i2c_block_data(chip->client,
> + if (i2c_check_functionality(chip->client->adapter,
> + I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
> + return i2c_smbus_write_i2c_block_data(chip->client,
> (reg << bank_shift) | REG_ADDR_AI,
> NBANK(chip), val);
> + } else {
Redundant and makes useless indentation level below.
> + for (i = 0; i < NBANK(chip); i++) {
> + ret = i2c_smbus_write_byte_data(chip->client,
> + (reg << 1) + i, val[i]);
> + if (ret < 0)
> + return ret;
> + }
> + return ret;
> + }
> }
>
> static int pca953x_write_regs(struct pca953x_chip *chip, int reg, u8 *val)
> @@ -249,7 +261,7 @@ static int pca953x_read_regs_24(struct pca953x_chip *chip, int reg, u8 *val)
> {
> int bank_shift = fls((chip->gpio_chip.ngpio - 1) / BANK_SZ);
>
> - return i2c_smbus_read_i2c_block_data(chip->client,
> + return i2c_smbus_read_i2c_block_data_or_emulated(chip->client,
> (reg << bank_shift) | REG_ADDR_AI,
> NBANK(chip), val);
Don't we have a counter part for writing?
Perhaps, it might be another option.
--
With Best Regards,
Andy Shevchenko
next prev parent reply other threads:[~2017-12-29 9:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-05 2:17 [PATCH] gpio-pca953x: fall back to byte-at-a-time for 24-bit io Andrew Cooks
2017-12-29 9:44 ` Andy Shevchenko [this message]
2018-01-29 4:11 ` Andrew Cooks
2018-02-08 12:10 ` Jean Delvare
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