linux-kernel - Re: [PATCH 1/4] drm/dp: Use seq_putc() in drm_dp_mst_dump

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Message-ID: <1493658687.6621.3.camel@perches.com>
Date:   Mon, 01 May 2017 10:11:27 -0700
From:   Joe Perches <joe@...ches.com>
To:     SF Markus Elfring <elfring@...rs.sourceforge.net>,
        dri-devel@...ts.freedesktop.org,
        Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Sean Paul <seanpaul@...omium.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 1/4] drm/dp: Use seq_putc() in drm_dp_mst_dump_topology()

On Mon, 2017-05-01 at 18:46 +0200, SF Markus Elfring wrote:
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Mon, 1 May 2017 17:08:56 +0200
> 
> A few single characters (line breaks) should be put into a sequence.
> Thus use the corresponding function "seq_putc".
> 
> This issue was detected by using the Coccinelle software.
[]
> diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
[]
> @@ -2840,17 +2840,17 @@ void drm_dp_mst_dump_topology(struct seq_file *m,
>  		seq_printf(m, "dpcd: ");
>  		for (i = 0; i < DP_RECEIVER_CAP_SIZE; i++)
>  			seq_printf(m, "%02x ", buf[i]);
> -		seq_printf(m, "\n");
> +		seq_putc(m, '\n');
>  		ret = drm_dp_dpcd_read(mgr->aux, DP_FAUX_CAP, buf, 2);
>  		seq_printf(m, "faux/mst: ");
>  		for (i = 0; i < 2; i++)
>  			seq_printf(m, "%02x ", buf[i]);
> -		seq_printf(m, "\n");
> +		seq_putc(m, '\n');
>  		ret = drm_dp_dpcd_read(mgr->aux, DP_MSTM_CTRL, buf, 1);
>  		seq_printf(m, "mst ctrl: ");
>  		for (i = 0; i < 1; i++)
>  			seq_printf(m, "%02x ", buf[i]);
> -		seq_printf(m, "\n");
> +		seq_putc(m, '\n');

Please don't be _just_ mechanical.

Stop and read the code the tools you use using
suggest modifying and see how you can improve
it for a human reader.

If you're really trying to improve these to make
them more readable or smaller object code size, 
you should use the vsprintf extensions like:

		seq_printf(m, "dpcd: %*ph\n", DP_RECEIVER_CAP_SIZE, buf);

And if these are supposed to be correct, then
the return value from drm_dp_dpcd_read should
be tested too.

Likely these repeated code blocks could be put
into a helper function.