linux-kernel - Re: [PATCH] media: stv090x: add missed checks for STV090x_WRITE

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Date:   Thu, 4 Apr 2019 20:47:33 +0100
From:   Sean Young <sean@...s.org>
To:     Kangjie Lu <kjlu@....edu>
Cc:     pakki001@....edu, Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: stv090x: add missed checks for STV090x_WRITE_DEMOD

On Fri, Mar 22, 2019 at 09:46:13PM -0500, Kangjie Lu wrote:
> Conservatively check return value of STV090x_WRITE_DEMOD in case
> it fails.

This can introduce regressions. It is very possible that the return value
was not checked for a reason. So, this has to be tested on hardware.


Sean

> 
> Signed-off-by: Kangjie Lu <kjlu@....edu>
> ---
>  drivers/media/dvb-frontends/stv090x.c | 19 +++++++++++++------
>  1 file changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/media/dvb-frontends/stv090x.c b/drivers/media/dvb-frontends/stv090x.c
> index a0622bb71803..3e2af3969e16 100644
> --- a/drivers/media/dvb-frontends/stv090x.c
> +++ b/drivers/media/dvb-frontends/stv090x.c
> @@ -1446,14 +1446,17 @@ static int stv090x_start_search(struct stv090x_state *state)
>  		/* >= Cut 3 */
>  		if (state->srate <= 5000000) {
>  			/* enlarge the timing bandwidth for Low SR */
> -			STV090x_WRITE_DEMOD(state, RTCS2, 0x68);
> +			if (STV090x_WRITE_DEMOD(state, RTCS2, 0x68) < 0)
> +				goto err;
>  		} else {
>  			/* reduce timing bandwidth for high SR */
> -			STV090x_WRITE_DEMOD(state, RTCS2, 0x44);
> +			if (STV090x_WRITE_DEMOD(state, RTCS2, 0x44) < 0)
> +				goto err;
>  		}
>  
>  		/* Set CFR min and max to manual mode */
> -		STV090x_WRITE_DEMOD(state, CARCFG, 0x46);
> +		if (STV090x_WRITE_DEMOD(state, CARCFG, 0x46) < 0)
> +			goto err;
>  
>  		if (state->algo == STV090x_WARM_SEARCH) {
>  			/* WARM Start
> @@ -2604,7 +2607,8 @@ static enum stv090x_signal_state stv090x_get_sig_params(struct stv090x_state *st
>  
>  	if (state->algo == STV090x_BLIND_SEARCH) {
>  		tmg = STV090x_READ_DEMOD(state, TMGREG2);
> -		STV090x_WRITE_DEMOD(state, SFRSTEP, 0x5c);
> +		if (STV090x_WRITE_DEMOD(state, SFRSTEP, 0x5c) < 0)
> +			goto err;
>  		while ((i <= 50) && (tmg != 0) && (tmg != 0xff)) {
>  			tmg = STV090x_READ_DEMOD(state, TMGREG2);
>  			msleep(5);
> @@ -2910,7 +2914,9 @@ static int stv090x_optimize_track(struct stv090x_state *state)
>  			pilots = STV090x_GETFIELD_Px(reg, DEMOD_TYPE_FIELD) & 0x01;
>  			aclc = stv090x_optimize_carloop(state, modcod, pilots);
>  			if (modcod <= STV090x_QPSK_910) {
> -				STV090x_WRITE_DEMOD(state, ACLC2S2Q, aclc);
> +				if (STV090x_WRITE_DEMOD(state, ACLC2S2Q, aclc)
> +						< 0)
> +					goto err;
>  			} else if (modcod <= STV090x_8PSK_910) {
>  				if (STV090x_WRITE_DEMOD(state, ACLC2S2Q, 0x2a) < 0)
>  					goto err;
> @@ -2972,7 +2978,8 @@ static int stv090x_optimize_track(struct stv090x_state *state)
>  	reg = STV090x_READ_DEMOD(state, TMGOBS);
>  
>  	if (state->algo == STV090x_BLIND_SEARCH) {
> -		STV090x_WRITE_DEMOD(state, SFRSTEP, 0x00);
> +		if (STV090x_WRITE_DEMOD(state, SFRSTEP, 0x00) < 0)
> +			goto err;
>  		reg = STV090x_READ_DEMOD(state, DMDCFGMD);
>  		STV090x_SETFIELD_Px(reg, SCAN_ENABLE_FIELD, 0x00);
>  		STV090x_SETFIELD_Px(reg, CFR_AUTOSCAN_FIELD, 0x00);
> -- 
> 2.17.1