# Re: \[PATCH 3/4\] \[resend \#2\] fb\_ddc: Allow I2C adapters without SCL read capability

- From: Ondrej Zary \<hidden\>
- Date: 2015-09-02 12:04:56 
- List: linux-fbdev
- Page: https://ratatoskr.run/linux-fbdev/2015/09/4568330
- Thread: https://ratatoskr.run/linux-fbdev/2015/08/4563090/t.md

```text
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 <redacted>
> > Acked-by: Krzysztof Helt <redacted>
> > ---
> >  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
```