linux-kernel - Re: [PATCH 3/4] [resend #2] fb_ddc: Allow I2C adapters without SCL read capability

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Date:	Wed, 2 Sep 2015 14:33:17 +0300
From:	Tomi Valkeinen <tomi.valkeinen@...com>
To:	Ondrej Zary <linux@...nbow-software.org>,
	Krzysztof Helt <krzysztof.h1@...pl>
CC:	<linux-fbdev@...r.kernel.org>,
	Kernel development list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/4] [resend #2] fb_ddc: Allow I2C adapters without SCL
 read capability



On 24/08/15 22:37, Ondrej Zary wrote:
> i2c-algo-bit allows I2C adapters without SCL read capability to work but
> fb_ddc_read fails to work on them.
> 
> Fix fb_ddc_read to work with I2C adapters not capable of reading SCL.
> 
> Signed-off-by: Ondrej Zary <linux@...nbow-software.org>
> Acked-by: Krzysztof Helt <krzysztof.h1@...pl>
> ---
>  drivers/video/fbdev/core/fb_ddc.c |    8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/video/fbdev/core/fb_ddc.c b/drivers/video/fbdev/core/fb_ddc.c
> index 94322cc..22c694a 100644
> --- a/drivers/video/fbdev/core/fb_ddc.c
> +++ b/drivers/video/fbdev/core/fb_ddc.c
> @@ -69,10 +69,11 @@ unsigned char *fb_ddc_read(struct i2c_adapter *adapter)
>  		algo_data->setscl(algo_data->data, 1);
>  		for (j = 0; j < 5; j++) {
>  			msleep(10);
> -			if (algo_data->getscl(algo_data->data))
> +			if (algo_data->getscl &&
> +			    algo_data->getscl(algo_data->data))
>  				break;
>  		}
> -		if (j == 5)
> +		if (algo_data->getscl && j == 5)
>  			continue;
>  
>  		algo_data->setsda(algo_data->data, 0);
> @@ -91,7 +92,8 @@ unsigned char *fb_ddc_read(struct i2c_adapter *adapter)
>  		algo_data->setscl(algo_data->data, 1);
>  		for (j = 0; j < 10; j++) {
>  			msleep(10);
> -			if (algo_data->getscl(algo_data->data))
> +			if (algo_data->getscl &&
> +			    algo_data->getscl(algo_data->data))
>  				break;
>  		}

Aren't both of those loops pointless if there's no getscl?

 Tomi


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