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

[Marek Vasut]

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?