RE: [PATCH v2 1/3] i2c: s3c24xx: fix read transfers in polling mode

["Chanho Park" <chanho61.park@samsung.com>]

> -----Original Message-----
> From: Marek Szyprowski <m.szyprowski@samsung.com>
> Sent: Wednesday, October 25, 2023 9:17 PM
> To: linux-samsung-soc@vger.kernel.org; linux-i2c@vger.kernel.org
> Cc: Marek Szyprowski <m.szyprowski@samsung.com>; Krzysztof Kozlowski
> <krzysztof.kozlowski@linaro.org>; Alim Akhtar <alim.akhtar@samsung.com>;
> Andi Shyti <andi.shyti@kernel.org>; Wolfram Sang <wsa@kernel.org>
> Subject: [PATCH v2 1/3] i2c: s3c24xx: fix read transfers in polling mode
> 
> To properly handle read transfers in polling mode, no waiting for the ACK
> state is needed as it will never come. Just wait a bit to ensure start
> state is on the bus and continue processing next bytes.
> 
> Fixes: 117053f77a5a ("i2c: s3c2410: Add polling mode support")
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

Reviewed-by: Chanho Park <chanho61.park@samsung.com>

> ---
>  drivers/i2c/busses/i2c-s3c2410.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-
> s3c2410.c
> index 127eb3805fac..f9dcb1112a61 100644
> --- a/drivers/i2c/busses/i2c-s3c2410.c
> +++ b/drivers/i2c/busses/i2c-s3c2410.c
> @@ -216,8 +216,13 @@ static bool is_ack(struct s3c24xx_i2c *i2c)
>  	int tries;
> 
>  	for (tries = 50; tries; --tries) {
> -		if (readl(i2c->regs + S3C2410_IICCON)
> -			& S3C2410_IICCON_IRQPEND) {
> +		unsigned long tmp = readl(i2c->regs + S3C2410_IICCON);
> +
> +		if (!(tmp & S3C2410_IICCON_ACKEN)) {
> +			usleep_range(100, 200);
> +			return true;
> +		}
> +		if (tmp & S3C2410_IICCON_IRQPEND) {
>  			if (!(readl(i2c->regs + S3C2410_IICSTAT)
>  				& S3C2410_IICSTAT_LASTBIT))
>  				return true;
> --
> 2.34.1