linux-kernel - Re: [PATCH 1/1] net: dsa: rtl8366rb: standardize init jam tables

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Message-ID: <20210126223700.d3wdlf264ox7ea2w@skbuf>
Date:   Wed, 27 Jan 2021 00:37:00 +0200
From:   Vladimir Oltean <olteanv@...il.com>
To:     Lorenzo Carletti <lorenzo.carletti98@...il.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>, andrew@...n.ch,
        vivien.didelot@...il.com, f.fainelli@...il.com,
        davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] net: dsa: rtl8366rb: standardize init jam tables

On Wed, Jan 27, 2021 at 12:28:05AM +0200, Vladimir Oltean wrote:
> > So, allow me to explain. The kernel jams every "i + 1" value in the array
> > tables into the registers at " i", and then increments "i" by 2.
> > These can be seen as [n][2] matrixes, just like the ethernet one.
> > Having the arrays converted to matrixes can help visualize which
> > value is jammed where, or at least that's how I feel like it is.
> > I know it's not a big change...
> 
> Got it, thanks. It is better, in fact, once you get over that whole
> 0xBE00 thing...

If you really want beautiful code, I guess you could create a structure
with two fields:

struct rtl8366rb_jam_table_entry {
	u16 addr;
	u16 val;
};

and then convert those ugly looking matrix definitions:
u16 (*jam_table)[2]
with:
struct rtl8366rb_jam_table_entry *jam_table

and this:
		ret = regmap_write(smi->map,
				   jam_table[i][0],
				   jam_table[i][1]);
with this:
		ret = regmap_write(smi->map,
				   jam_table[i].addr,
				   jam_table[i].val);

The memory footprint would be exactly the same, and the struct
initializers would look exactly the same as your current array
declarations.