Re: [PATCH v2 4/9] drm/panel: Add driver for the LG Philips LB035Q02 panel

From: Sam Ravnborg <sam@ravnborg.org>
To: "Noralf Trønnes" <noralf@tronnes.org>
Cc: Thierry Reding <thierry.reding@gmail.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v2 4/9] drm/panel: Add driver for the LG Philips LB035Q02 panel
Date: Sun, 11 Aug 2019 19:26:38 +0200	[thread overview]
Message-ID: <20190811172638.GA20098@ravnborg.org> (raw)
In-Reply-To: <19674e30-bbc2-6cc7-856f-7488d7173dc6@tronnes.org>

Hi Noralf.

> >>> +	/* register value */
> >>> +	buffer[4] = 0x72;
> >>> +	buffer[5] = val >> 8;
> >>> +	buffer[6] = val;
> >>> +	value_xfer.tx_buf = buffer + 4;
> >>> +	spi_message_add_tail(&value_xfer, &msg);
> >>> +
> >>> +	return spi_sync(lcd->spi, &msg);
> >>> +}
> >>
> >> Just a note to Sam:
> >> This is the same spi protocol that the ili9325 controller on the hy28b
> >> panel uses.
> >>
> >> I remembered that I have experimented with a regmap implementation:
> >> https://github.com/notro/tinydrm/blob/master/tinydrm-ili9325.c#L191
> > 
> > regmap seems a too limited interface to use when trying to generalize
> > this.
> > We should rather go for a ili-lib or something that can be used in all
> > the present and future ili based drivers.
> > Obviously it depends on how similar the ili based chips are.
> > 
> > I did a quick look and this driver did not match the ili9325 datasheet
> > as different bits was are in register 0x1.
> > So it smeels like another, similar. ili varaint.
> > 
> > So for this driver we would just use the hardcoded varaint already
> > present. Then we may re-visit ili-lib idea later if we see too much
> > similar code.
> > This is as I see it for now...
> > 
> 
> Yeah, no point in changing this driver until there are more similar
> controllers. Just wanted to point out that the hy28b panel you ordered
> uses the same protocol.
Ohh, that was your point. Thanks!

The display is still in the mail somewhere from China..
Right now I do not have time to hack on it so not a big deal.

For the fun of it I ordred a few other displays. One was ssd1306 based,
and do not recall the rest.

	Sam

> 
> A web search helped my memory, these 3 supported by staging/fbtft use a
> startbyte: ili9320, ili9325 and hx8347d. The ili chips are almost
> identical. The search revealed many more including:
> st7793, st7781r, S6E63D6, +many ilitek.
> 
> Noralf.
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