Re: [PATCH v3] media: si2168: Refactor command setup code

[Brad Love <brad@nextdimension.cc>]

Hi Marc,

Replying inline.


On 04/07/2019 05.33, Marc Gonzalez wrote:
> Refactor the command setup code, and let the compiler determine
> the size of each command.
>
> Reviewed-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
> Signed-off-by: Marc Gonzalez <marc.w.gonzalez@free.fr>
> ---
> Changes from v1:
> - Use a real function to populate struct si2168_cmd *cmd, and a trivial
> macro wrapping it (macro because sizeof).
> Changes from v2:
> - Fix header mess
> - Add Jonathan's tag
> ---
>  drivers/media/dvb-frontends/si2168.c | 146 +++++++++------------------
>  1 file changed, 45 insertions(+), 101 deletions(-)
>
> diff --git a/drivers/media/dvb-frontends/si2168.c b/drivers/media/dvb-frontends/si2168.c
> index c64b360ce6b5..5e81e076369c 100644
> --- a/drivers/media/dvb-frontends/si2168.c
> +++ b/drivers/media/dvb-frontends/si2168.c
> @@ -12,6 +12,16 @@
>  
>  static const struct dvb_frontend_ops si2168_ops;
>  
> +static void cmd_setup(struct si2168_cmd *cmd, char *args, int wlen, int rlen)
> +{
> +	memcpy(cmd->args, args, wlen);
> +	cmd->wlen = wlen;
> +	cmd->rlen = rlen;
> +}
> +


struct si2168_cmd.args is u8, not char. I also think const should apply
to the pointer.


> +#define CMD_SETUP(cmd, args, rlen) \
> +	cmd_setup(cmd, args, sizeof(args) - 1, rlen)
> +


This is only a valid helper if args is a null terminated string. It just
so happens that every instance in this driver is, but that could be a
silent pitfall if someone used a u8 array with this macro.

Otherwise I'm ok with the refactoring.

Regards,

Brad




>  /* execute firmware command */
>  static int si2168_cmd_execute(struct i2c_client *client, struct si2168_cmd *cmd)
>  {
> @@ -84,15 +94,13 @@ static int si2168_ts_bus_ctrl(struct dvb_frontend *fe, int acquire)
>  	dev_dbg(&client->dev, "%s acquire: %d\n", __func__, acquire);
>  
>  	/* set TS_MODE property */
> -	memcpy(cmd.args, "\x14\x00\x01\x10\x10\x00", 6);
> +	CMD_SETUP(&cmd, "\x14\x00\x01\x10\x10\x00", 4);
>  	if (acquire)
>  		cmd.args[4] |= dev->ts_mode;
>  	else
>  		cmd.args[4] |= SI2168_TS_TRISTATE;
>  	if (dev->ts_clock_gapped)
>  		cmd.args[4] |= 0x40;
> -	cmd.wlen = 6;
> -	cmd.rlen = 4;
>  	ret = si2168_cmd_execute(client, &cmd);
>  
>  	return ret;
> @@ -116,19 +124,13 @@ static int si2168_read_status(struct dvb_frontend *fe, enum fe_status *status)
>  
>  	switch (c->delivery_system) {
>  	case SYS_DVBT:
> -		memcpy(cmd.args, "\xa0\x01", 2);
> -		cmd.wlen = 2;
> -		cmd.rlen = 13;
> +		CMD_SETUP(&cmd, "\xa0\x01", 13);
>  		break;
>  	case SYS_DVBC_ANNEX_A:
> -		memcpy(cmd.args, "\x90\x01", 2);
> -		cmd.wlen = 2;
> -		cmd.rlen = 9;
> +		CMD_SETUP(&cmd, "\x90\x01", 9);
>  		break;
>  	case SYS_DVBT2:
> -		memcpy(cmd.args, "\x50\x01", 2);
> -		cmd.wlen = 2;
> -		cmd.rlen = 14;
> +		CMD_SETUP(&cmd, "\x50\x01", 14);
>  		break;
>  	default:
>  		ret = -EINVAL;
> @@ -165,9 +167,7 @@ static int si2168_read_status(struct dvb_frontend *fe, enum fe_status *status)
>  
>  	/* BER */
>  	if (*status & FE_HAS_VITERBI) {
> -		memcpy(cmd.args, "\x82\x00", 2);
> -		cmd.wlen = 2;
> -		cmd.rlen = 3;
> +		CMD_SETUP(&cmd, "\x82\x00", 3);
>  		ret = si2168_cmd_execute(client, &cmd);
>  		if (ret)
>  			goto err;
> @@ -198,9 +198,7 @@ static int si2168_read_status(struct dvb_frontend *fe, enum fe_status *status)
>  
>  	/* UCB */
>  	if (*status & FE_HAS_SYNC) {
> -		memcpy(cmd.args, "\x84\x01", 2);
> -		cmd.wlen = 2;
> -		cmd.rlen = 3;
> +		CMD_SETUP(&cmd, "\x84\x01", 3);
>  		ret = si2168_cmd_execute(client, &cmd);
>  		if (ret)
>  			goto err;
> @@ -286,22 +284,18 @@ static int si2168_set_frontend(struct dvb_frontend *fe)
>  			goto err;
>  	}
>  
> -	memcpy(cmd.args, "\x88\x02\x02\x02\x02", 5);
> -	cmd.wlen = 5;
> -	cmd.rlen = 5;
> +	CMD_SETUP(&cmd, "\x88\x02\x02\x02\x02", 5);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
>  
>  	/* that has no big effect */
>  	if (c->delivery_system == SYS_DVBT)
> -		memcpy(cmd.args, "\x89\x21\x06\x11\xff\x98", 6);
> +		CMD_SETUP(&cmd, "\x89\x21\x06\x11\xff\x98", 3);
>  	else if (c->delivery_system == SYS_DVBC_ANNEX_A)
> -		memcpy(cmd.args, "\x89\x21\x06\x11\x89\xf0", 6);
> +		CMD_SETUP(&cmd, "\x89\x21\x06\x11\x89\xf0", 3);
>  	else if (c->delivery_system == SYS_DVBT2)
> -		memcpy(cmd.args, "\x89\x21\x06\x11\x89\x20", 6);
> -	cmd.wlen = 6;
> -	cmd.rlen = 3;
> +		CMD_SETUP(&cmd, "\x89\x21\x06\x11\x89\x20", 3);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
> @@ -318,103 +312,77 @@ static int si2168_set_frontend(struct dvb_frontend *fe)
>  			goto err;
>  	}
>  
> -	memcpy(cmd.args, "\x51\x03", 2);
> -	cmd.wlen = 2;
> -	cmd.rlen = 12;
> +	CMD_SETUP(&cmd, "\x51\x03", 12);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
>  
> -	memcpy(cmd.args, "\x12\x08\x04", 3);
> -	cmd.wlen = 3;
> -	cmd.rlen = 3;
> +	CMD_SETUP(&cmd, "\x12\x08\x04", 3);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
>  
> -	memcpy(cmd.args, "\x14\x00\x0c\x10\x12\x00", 6);
> -	cmd.wlen = 6;
> -	cmd.rlen = 4;
> +	CMD_SETUP(&cmd, "\x14\x00\x0c\x10\x12\x00", 4);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
>  
> -	memcpy(cmd.args, "\x14\x00\x06\x10\x24\x00", 6);
> -	cmd.wlen = 6;
> -	cmd.rlen = 4;
> +	CMD_SETUP(&cmd, "\x14\x00\x06\x10\x24\x00", 4);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
>  
> -	memcpy(cmd.args, "\x14\x00\x07\x10\x00\x24", 6);
> -	cmd.wlen = 6;
> -	cmd.rlen = 4;
> +	CMD_SETUP(&cmd, "\x14\x00\x07\x10\x00\x24", 4);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
>  
> -	memcpy(cmd.args, "\x14\x00\x0a\x10\x00\x00", 6);
> +	CMD_SETUP(&cmd, "\x14\x00\x0a\x10\x00\x00", 4);
>  	cmd.args[4] = delivery_system | bandwidth;
>  	if (dev->spectral_inversion)
>  		cmd.args[5] |= 1;
> -	cmd.wlen = 6;
> -	cmd.rlen = 4;
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
>  
>  	/* set DVB-C symbol rate */
>  	if (c->delivery_system == SYS_DVBC_ANNEX_A) {
> -		memcpy(cmd.args, "\x14\x00\x02\x11", 4);
> +		CMD_SETUP(&cmd, "\x14\x00\x02\x11\x00\x00", 4);
>  		cmd.args[4] = ((c->symbol_rate / 1000) >> 0) & 0xff;
>  		cmd.args[5] = ((c->symbol_rate / 1000) >> 8) & 0xff;
> -		cmd.wlen = 6;
> -		cmd.rlen = 4;
>  		ret = si2168_cmd_execute(client, &cmd);
>  		if (ret)
>  			goto err;
>  	}
>  
> -	memcpy(cmd.args, "\x14\x00\x0f\x10\x10\x00", 6);
> -	cmd.wlen = 6;
> -	cmd.rlen = 4;
> +	CMD_SETUP(&cmd, "\x14\x00\x0f\x10\x10\x00", 4);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
>  
> -	memcpy(cmd.args, "\x14\x00\x09\x10\xe3\x08", 6);
> +	CMD_SETUP(&cmd, "\x14\x00\x09\x10\xe3\x08", 4);
>  	cmd.args[5] |= dev->ts_clock_inv ? 0x00 : 0x10;
> -	cmd.wlen = 6;
> -	cmd.rlen = 4;
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
>  
> -	memcpy(cmd.args, "\x14\x00\x08\x10\xd7\x05", 6);
> +	CMD_SETUP(&cmd, "\x14\x00\x08\x10\xd7\x05", 4);
>  	cmd.args[5] |= dev->ts_clock_inv ? 0x00 : 0x10;
> -	cmd.wlen = 6;
> -	cmd.rlen = 4;
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
>  
> -	memcpy(cmd.args, "\x14\x00\x01\x12\x00\x00", 6);
> -	cmd.wlen = 6;
> -	cmd.rlen = 4;
> +	CMD_SETUP(&cmd, "\x14\x00\x01\x12\x00\x00", 4);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
>  
> -	memcpy(cmd.args, "\x14\x00\x01\x03\x0c\x00", 6);
> -	cmd.wlen = 6;
> -	cmd.rlen = 4;
> +	CMD_SETUP(&cmd, "\x14\x00\x01\x03\x0c\x00", 4);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
>  
> -	memcpy(cmd.args, "\x85", 1);
> -	cmd.wlen = 1;
> -	cmd.rlen = 1;
> +	CMD_SETUP(&cmd, "\x85", 1);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
> @@ -444,26 +412,20 @@ static int si2168_init(struct dvb_frontend *fe)
>  	dev_dbg(&client->dev, "\n");
>  
>  	/* initialize */
> -	memcpy(cmd.args, "\xc0\x12\x00\x0c\x00\x0d\x16\x00\x00\x00\x00\x00\x00", 13);
> -	cmd.wlen = 13;
> -	cmd.rlen = 0;
> +	CMD_SETUP(&cmd, "\xc0\x12\x00\x0c\x00\x0d\x16\x00\x00\x00\x00\x00\x00", 0);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
>  
>  	if (dev->warm) {
>  		/* resume */
> -		memcpy(cmd.args, "\xc0\x06\x08\x0f\x00\x20\x21\x01", 8);
> -		cmd.wlen = 8;
> -		cmd.rlen = 1;
> +		CMD_SETUP(&cmd, "\xc0\x06\x08\x0f\x00\x20\x21\x01", 1);
>  		ret = si2168_cmd_execute(client, &cmd);
>  		if (ret)
>  			goto err;
>  
>  		udelay(100);
> -		memcpy(cmd.args, "\x85", 1);
> -		cmd.wlen = 1;
> -		cmd.rlen = 1;
> +		CMD_SETUP(&cmd, "\x85", 1);
>  		ret = si2168_cmd_execute(client, &cmd);
>  		if (ret)
>  			goto err;
> @@ -472,9 +434,7 @@ static int si2168_init(struct dvb_frontend *fe)
>  	}
>  
>  	/* power up */
> -	memcpy(cmd.args, "\xc0\x06\x01\x0f\x00\x20\x20\x01", 8);
> -	cmd.wlen = 8;
> -	cmd.rlen = 1;
> +	CMD_SETUP(&cmd, "\xc0\x06\x01\x0f\x00\x20\x20\x01", 1);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
> @@ -542,17 +502,13 @@ static int si2168_init(struct dvb_frontend *fe)
>  
>  	release_firmware(fw);
>  
> -	memcpy(cmd.args, "\x01\x01", 2);
> -	cmd.wlen = 2;
> -	cmd.rlen = 1;
> +	CMD_SETUP(&cmd, "\x01\x01", 1);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
>  
>  	/* query firmware version */
> -	memcpy(cmd.args, "\x11", 1);
> -	cmd.wlen = 1;
> -	cmd.rlen = 10;
> +	CMD_SETUP(&cmd, "\x11", 10);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
> @@ -610,9 +566,7 @@ static int si2168_sleep(struct dvb_frontend *fe)
>  	if (dev->version > ('B' << 24 | 4 << 16 | 0 << 8 | 11 << 0))
>  		dev->warm = false;
>  
> -	memcpy(cmd.args, "\x13", 1);
> -	cmd.wlen = 1;
> -	cmd.rlen = 0;
> +	CMD_SETUP(&cmd, "\x13", 0);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
> @@ -638,9 +592,7 @@ static int si2168_select(struct i2c_mux_core *muxc, u32 chan)
>  	struct si2168_cmd cmd;
>  
>  	/* open I2C gate */
> -	memcpy(cmd.args, "\xc0\x0d\x01", 3);
> -	cmd.wlen = 3;
> -	cmd.rlen = 0;
> +	CMD_SETUP(&cmd, "\xc0\x0d\x01", 0);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
> @@ -658,9 +610,7 @@ static int si2168_deselect(struct i2c_mux_core *muxc, u32 chan)
>  	struct si2168_cmd cmd;
>  
>  	/* close I2C gate */
> -	memcpy(cmd.args, "\xc0\x0d\x00", 3);
> -	cmd.wlen = 3;
> -	cmd.rlen = 0;
> +	CMD_SETUP(&cmd, "\xc0\x0d\x00", 0);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err;
> @@ -753,25 +703,19 @@ static int si2168_probe(struct i2c_client *client,
>  	mutex_init(&dev->i2c_mutex);
>  
>  	/* Initialize */
> -	memcpy(cmd.args, "\xc0\x12\x00\x0c\x00\x0d\x16\x00\x00\x00\x00\x00\x00", 13);
> -	cmd.wlen = 13;
> -	cmd.rlen = 0;
> +	CMD_SETUP(&cmd, "\xc0\x12\x00\x0c\x00\x0d\x16\x00\x00\x00\x00\x00\x00", 0);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err_kfree;
>  
>  	/* Power up */
> -	memcpy(cmd.args, "\xc0\x06\x01\x0f\x00\x20\x20\x01", 8);
> -	cmd.wlen = 8;
> -	cmd.rlen = 1;
> +	CMD_SETUP(&cmd, "\xc0\x06\x01\x0f\x00\x20\x20\x01", 1);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err_kfree;
>  
>  	/* Query chip revision */
> -	memcpy(cmd.args, "\x02", 1);
> -	cmd.wlen = 1;
> -	cmd.rlen = 13;
> +	CMD_SETUP(&cmd, "\x02", 13);
>  	ret = si2168_cmd_execute(client, &cmd);
>  	if (ret)
>  		goto err_kfree;