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 14:04:51 +0200
From:	Ondrej Zary <linux@...nbow-software.org>
To:	Tomi Valkeinen <tomi.valkeinen@...com>
Cc:	Krzysztof Helt <krzysztof.h1@...pl>, 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 Wednesday 02 September 2015, Tomi Valkeinen wrote:
> 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?

They're reduced to delays - don't know how much critical they are.

-- 
Ondrej Zary
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