[PATCH V2 04/12] drm: bridge: icn6211: Add DSI lane count DT property parsing

[Maxime Ripard]

On Wed, Mar 02, 2022 at 04:17:04PM +0100, Marek Vasut wrote:
> On 3/2/22 11:01, Maxime Ripard wrote:
> > On Thu, Feb 17, 2022 at 01:25:22AM +0100, Marek Vasut wrote:
> > > The driver currently hard-codes DSI lane count to two, however the chip
> > > is capable of operating in 1..4 DSI lanes mode. Parse 'data-lanes' DT
> > > property and program the result into DSI_CTRL register.
> > > 
> > > Signed-off-by: Marek Vasut <marex at denx.de>
> > > Cc: Jagan Teki <jagan at amarulasolutions.com>
> > > Cc: Maxime Ripard <maxime at cerno.tech>
> > > Cc: Robert Foss <robert.foss at linaro.org>
> > > Cc: Sam Ravnborg <sam at ravnborg.org>
> > > Cc: Thomas Zimmermann <tzimmermann at suse.de>
> > > To: dri-devel at lists.freedesktop.org
> > > ---
> > > V2: Rebase on next-20220214
> > > ---
> > >   drivers/gpu/drm/bridge/chipone-icn6211.c | 21 ++++++++++++++++++++-
> > >   1 file changed, 20 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/gpu/drm/bridge/chipone-icn6211.c b/drivers/gpu/drm/bridge/chipone-icn6211.c
> > > index 2ac8eb7e25f52..7c013a08c7b00 100644
> > > --- a/drivers/gpu/drm/bridge/chipone-icn6211.c
> > > +++ b/drivers/gpu/drm/bridge/chipone-icn6211.c
> > > @@ -136,10 +136,12 @@ struct chipone {
> > >   	struct drm_bridge bridge;
> > >   	struct drm_display_mode mode;
> > >   	struct drm_bridge *panel_bridge;
> > > +	struct device_node *host_node;
> > >   	struct gpio_desc *enable_gpio;
> > >   	struct regulator *vdd1;
> > >   	struct regulator *vdd2;
> > >   	struct regulator *vdd3;
> > > +	int dsi_lanes;
> > >   };
> > >   static inline struct chipone *bridge_to_chipone(struct drm_bridge *bridge)
> > > @@ -212,6 +214,11 @@ static void chipone_atomic_enable(struct drm_bridge *bridge,
> > >   	/* dsi specific sequence */
> > >   	ICN6211_DSI(icn, SYNC_EVENT_DLY, 0x80);
> > >   	ICN6211_DSI(icn, HFP_MIN, hfp & 0xff);
> > > +
> > > +	/* DSI data lane count */
> > > +	ICN6211_DSI(icn, DSI_CTRL,
> > > +		    DSI_CTRL_UNKNOWN | DSI_CTRL_DSI_LANES(icn->dsi_lanes - 1));
> > > +
> > >   	ICN6211_DSI(icn, MIPI_PD_CK_LANE, 0xa0);
> > >   	ICN6211_DSI(icn, PLL_CTRL(12), 0xff);
> > > @@ -314,6 +321,7 @@ static const struct drm_bridge_funcs chipone_bridge_funcs = {
> > >   static int chipone_parse_dt(struct chipone *icn)
> > >   {
> > >   	struct device *dev = icn->dev;
> > > +	struct device_node *endpoint;
> > >   	struct drm_panel *panel;
> > >   	int ret;
> > > @@ -350,6 +358,16 @@ static int chipone_parse_dt(struct chipone *icn)
> > >   		return PTR_ERR(icn->enable_gpio);
> > >   	}
> > > +	endpoint = of_graph_get_endpoint_by_regs(dev->of_node, 0, 0);
> > > +	icn->dsi_lanes = of_property_count_u32_elems(endpoint, "data-lanes");
> > 
> > The binding must be amended to allow for the usage of data-lanes, and
> > you need to keep the previous value as default for older device trees
> 
> Regarding the default value -- there are no in-tree users of this driver yet
> (per git grep in current linux-next), do we really care about backward
> compatibility in this case?

If it hasn't been in a stable release yet, no. If it did, yes

Maxime
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