Re: [PATCH v2 26/27] drm/tegra: Add DSI support

[Thierry Reding <thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

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On Mon, Oct 14, 2013 at 12:16:48PM -0600, Stephen Warren wrote:
> On 10/14/2013 07:55 AM, Thierry Reding wrote:
> > On Fri, Oct 11, 2013 at 04:43:35PM -0600, Stephen Warren wrote:
> >> On 10/07/2013 02:34 AM, Thierry Reding wrote:
> >>> This commit adds support for both DSI outputs found on Tegra. Only very
> >>> minimal functionality is implemented, so advanced features like ganged
> >>> mode won't work.
> >>>
> >>> Due to the lack of other test hardware, some sections of the driver are
> >>> hardcoded to work with Dalmore.
> >>
> >>> diff --git a/drivers/gpu/drm/tegra/dsi.c b/drivers/gpu/drm/tegra/dsi.c
> >>
> >>> +static int tegra_dsi_show_regs(struct seq_file *s, void *data)
> >>> +{
> >>> +	struct drm_info_node *node = s->private;
> >>> +	struct tegra_dsi *dsi = node->info_ent->data;
> >>> +
> >>> +#define DUMP_REG(name)						\
> >>> +	seq_printf(s, "%-32s %#05x %08lx\n", #name, name,	\
> >>> +		   tegra_dsi_readl(dsi, name))
> >>> +
> >>> +	DUMP_REG(DSI_INCR_SYNCPT);
> >>
> >> Does it make sense to use an MMIO regmap instead? That way, you get all
> >> the debugfs files for free...
> > 
> > As far as I know, regmap doesn't give you the symbolic names for the
> > registers. I find that a rather useful feature because it allows to
> > easily compare the registers to the ones in our downstream kernels.
> 
> True. However, we should really be writing user-space scripts to encode
> that information. Such a script could be useful e.g. if reading the
> information directly from /dev/mem or JTAG too, and bloating the kernel
> with debug strings doesn't seem like a great idea.

I don't agree. While I see some value in having such userspace scripts,
having the symbolic names in debugfs allows anyone to look at a readable
form of the data without having to have access to those scripts. Besides
it's called *debug*fs for a purpose, isn't it? There's plenty of edited
data that's not just a plain dump of data.

Thierry

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