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SubjectRe: [PATCH v3 1/3] drm/bridge: tfp410: Support basic I2C interface
On 20/02/2023 23:10, Jonathan Cormier wrote:
> From: Michael Williamson <michael.williamson@criticallink.com>
>
> The TFP410 driver does not support I2C. As such, the device remains in
> Power Down if the I2C is enabled by the bootstrap pins.
>
> Add basic support for the I2C interface, and provide support to take
> the device out of power down when enabled. Also read the bootstrap mode
> pins via the CTL_1_MODE register when using the I2C bus.
>
> Signed-off-by: Michael Williamson <michael.williamson@criticallink.com>
> Signed-off-by: Jonathan Cormier <jcormier@criticallink.com>
> ---
> drivers/gpu/drm/bridge/ti-tfp410.c | 93 +++++++++++++++++++++++++++-----------
> 1 file changed, 67 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/ti-tfp410.c b/drivers/gpu/drm/bridge/ti-tfp410.c
> index b9635abbad16..bb3f8d0ff207 100644
> --- a/drivers/gpu/drm/bridge/ti-tfp410.c
> +++ b/drivers/gpu/drm/bridge/ti-tfp410.c
> @@ -6,6 +6,7 @@
>
> #include <linux/gpio/consumer.h>
> #include <linux/i2c.h>
> +#include <linux/regmap.h>
> #include <linux/media-bus-format.h>
> #include <linux/module.h>
> #include <linux/of_graph.h>
> @@ -21,6 +22,20 @@
>
> #define HOTPLUG_DEBOUNCE_MS 1100
>
> +#define TFP410_REG_CTL_1_MODE 0x08
> +#define TFP410_BIT_PD BIT(0)
> +#define TFP410_BIT_EDGE BIT(1)
> +#define TFP410_BIT_BSEL BIT(2)
> +#define TFP410_BIT_DSEL BIT(3)
> +
> +static const struct regmap_config tfp410_regmap_config = {
> + .reg_bits = 8,
> + .val_bits = 8,
> +
> + .max_register = 0xff,
> + .cache_type = REGCACHE_NONE,
> +};
> +
> struct tfp410 {
> struct drm_bridge bridge;
> struct drm_connector connector;
> @@ -33,6 +48,8 @@ struct tfp410 {
> struct drm_bridge *next_bridge;
>
> struct device *dev;
> + struct i2c_client *i2c;
> + struct regmap *regmap;
> };
>
> static inline struct tfp410 *
> @@ -183,6 +200,9 @@ static void tfp410_enable(struct drm_bridge *bridge)
> {
> struct tfp410 *dvi = drm_bridge_to_tfp410(bridge);
>
> + if (dvi->i2c)
> + regmap_set_bits(dvi->regmap, TFP410_REG_CTL_1_MODE, TFP410_BIT_PD);
> +
> gpiod_set_value_cansleep(dvi->powerdown, 0);
> }
>
> @@ -190,6 +210,9 @@ static void tfp410_disable(struct drm_bridge *bridge)
> {
> struct tfp410 *dvi = drm_bridge_to_tfp410(bridge);
>
> + if (dvi->i2c)
> + regmap_clear_bits(dvi->regmap, TFP410_REG_CTL_1_MODE, TFP410_BIT_PD);
> +
> gpiod_set_value_cansleep(dvi->powerdown, 1);
> }
>
> @@ -221,38 +244,48 @@ static const struct drm_bridge_timings tfp410_default_timings = {
> .hold_time_ps = 1300,
> };
>
> -static int tfp410_parse_timings(struct tfp410 *dvi, bool i2c)
> +static int tfp410_parse_timings(struct tfp410 *dvi)
> {
> struct drm_bridge_timings *timings = &dvi->timings;
> struct device_node *ep;
> u32 pclk_sample = 0;
> u32 bus_width = 24;
> u32 deskew = 0;
> + unsigned int val = 0;
> + int ret = 0;
>
> /* Start with defaults. */
> *timings = tfp410_default_timings;
>
> - if (i2c)
> + if (dvi->i2c) {
> /*
> - * In I2C mode timings are configured through the I2C interface.
> - * As the driver doesn't support I2C configuration yet, we just
> - * go with the defaults (BSEL=1, DSEL=1, DKEN=0, EDGE=1).
> + * For now, assume settings are latched from pins on reset / power up.
> + * Should add options to optionally set them out of DT properties.
> */
> - return 0;
> -
> - /*
> - * In non-I2C mode, timings are configured through the BSEL, DSEL, DKEN
> - * and EDGE pins. They are specified in DT through endpoint properties
> - * and vendor-specific properties.
> - */
> - ep = of_graph_get_endpoint_by_regs(dvi->dev->of_node, 0, 0);
> - if (!ep)
> - return -EINVAL;
> -
> - /* Get the sampling edge from the endpoint. */
> - of_property_read_u32(ep, "pclk-sample", &pclk_sample);
> - of_property_read_u32(ep, "bus-width", &bus_width);
> - of_node_put(ep);
> + ret = regmap_read(dvi->regmap, TFP410_REG_CTL_1_MODE, &val);
> + if (ret) {
> + dev_err(dvi->dev, "Read failed on CTL_1_MODE\n");
> + return ret;
> + }
> + pclk_sample = (val & TFP410_BIT_EDGE) ? 1 : 0;
> + bus_width = (val & TFP410_BIT_BSEL) ? 24 : 12;
> + dev_dbg(dvi->dev, "(0x%02X) : detected %d bus width, %s edge sampling\n",
> + val, bus_width, pclk_sample ? "positive" : "negative");
> + } else {
> + /*
> + * In non-I2C mode, timings are configured through the BSEL, DSEL, DKEN
> + * and EDGE pins. They are specified in DT through endpoint properties
> + * and vendor-specific properties.
> + */
> + ep = of_graph_get_endpoint_by_regs(dvi->dev->of_node, 0, 0);
> + if (!ep)
> + return -EINVAL;
> +
> + /* Get the sampling edge from the endpoint. */
> + of_property_read_u32(ep, "pclk-sample", &pclk_sample);
> + of_property_read_u32(ep, "bus-width", &bus_width);
> + of_node_put(ep);
> + }
>
> timings->input_bus_flags = DRM_BUS_FLAG_DE_HIGH;
>
> @@ -291,7 +324,7 @@ static int tfp410_parse_timings(struct tfp410 *dvi, bool i2c)
> return 0;
> }
>
> -static int tfp410_init(struct device *dev, bool i2c)
> +static int tfp410_init(struct device *dev, struct i2c_client *i2c)
> {
> struct device_node *node;
> struct tfp410 *dvi;
> @@ -313,15 +346,24 @@ static int tfp410_init(struct device *dev, bool i2c)
> dvi->bridge.of_node = dev->of_node;
> dvi->bridge.timings = &dvi->timings;
> dvi->bridge.type = DRM_MODE_CONNECTOR_DVID;
> + dvi->i2c = i2c;
> +
> + if (i2c) {
> + dvi->regmap = devm_regmap_init_i2c(i2c, &tfp410_regmap_config);
> + if (IS_ERR(dvi->regmap))
> + return PTR_ERR(dvi->regmap);
> + }
>
> - ret = tfp410_parse_timings(dvi, i2c);
> + ret = tfp410_parse_timings(dvi);
> if (ret)
> return ret;
>
> /* Get the next bridge, connected to port@1. */
> node = of_graph_get_remote_node(dev->of_node, 1, -1);
> - if (!node)
> + if (!node) {
> + dev_err(dev, "Could not find remote node\n");
> return -ENODEV;
> + }
>
> dvi->next_bridge = of_drm_find_bridge(node);
> of_node_put(node);
> @@ -352,7 +394,7 @@ static void tfp410_fini(struct device *dev)
>
> static int tfp410_probe(struct platform_device *pdev)
> {
> - return tfp410_init(&pdev->dev, false);
> + return tfp410_init(&pdev->dev, NULL);
> }
>
> static int tfp410_remove(struct platform_device *pdev)
> @@ -378,7 +420,6 @@ static struct platform_driver tfp410_platform_driver = {
> };
>
> #if IS_ENABLED(CONFIG_I2C)
> -/* There is currently no i2c functionality. */
> static int tfp410_i2c_probe(struct i2c_client *client,
> const struct i2c_device_id *id)
> {
> @@ -391,7 +432,7 @@ static int tfp410_i2c_probe(struct i2c_client *client,
> return -ENXIO;
> }
>
> - return tfp410_init(&client->dev, true);
> + return tfp410_init(&client->dev, client);
> }
>
> static void tfp410_i2c_remove(struct i2c_client *client)
>

Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>

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