Re: [PATCH] xc2028: disable device power-down because power state handling is broken

[Mauro Carvalho Chehab <m.chehab@samsung.com>]

Em Mon, 30 Dec 2013 14:37:58 +0100
Frank Schäfer <fschaefer.oss@googlemail.com> escreveu:

> xc2028 power state handling is broken.
> I2C read/write operations fail when the device is powered down at that moment,
> which causes the get_rf_strength and get_rf_strength callbacks (and probably
> others, too) to fail.
> I don't know how to fix this properly, so disable the device power-down until
> anyone comes up with a better solution.
> 
> Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
> ---
>  drivers/media/tuners/tuner-xc2028.c |    4 +++-
>  1 Datei geändert, 3 Zeilen hinzugefügt(+), 1 Zeile entfernt(-)
> 
> diff --git a/drivers/media/tuners/tuner-xc2028.c b/drivers/media/tuners/tuner-xc2028.c
> index 4be5cf8..cb3dc5e 100644
> --- a/drivers/media/tuners/tuner-xc2028.c
> +++ b/drivers/media/tuners/tuner-xc2028.c
> @@ -1291,16 +1291,18 @@ static int xc2028_sleep(struct dvb_frontend *fe)
>  		dump_stack();
>  	}
>  
> +	/* FIXME: device power-up/-down handling is broken */
> +/*
>  	mutex_lock(&priv->lock);
>  
>  	if (priv->firm_version < 0x0202)
>  		rc = send_seq(priv, {0x00, XREG_POWER_DOWN, 0x00, 0x00});
>  	else
>  		rc = send_seq(priv, {0x80, XREG_POWER_DOWN, 0x00, 0x00});
> -
>  	priv->state = XC2028_SLEEP;
>  
>  	mutex_unlock(&priv->lock);
> +*/

This patch is completely broken.

First of all, there are both modprobe and config parameters that disables
the poweroff mode.

Second, it doesn't fix the bug, just hides it.

Third, it keeps the xc3028 energized, with spends power and heats the
device, with reduces its lifetime.

I'm working on a proper fix for it.

Cheers,
Mauro