linux-kernel - Re: [PATCH v2] drm/bridge: analogix-anx78xx: add support for 7808 addresses

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Message-ID: <20190920104945.GC12950@pendragon.ideasonboard.com>
Date:   Fri, 20 Sep 2019 13:49:45 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Brian Masney <masneyb@...tation.org>
Cc:     a.hajda@...sung.com, narmstrong@...libre.com, jonas@...boo.se,
        jernej.skrabec@...l.net, airlied@...ux.ie, daniel@...ll.ch,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        enric.balletbo@...labora.com
Subject: Re: [PATCH v2] drm/bridge: analogix-anx78xx: add support for 7808
 addresses

Hi Brian,

Thank you for the patch.

On Fri, Sep 20, 2019 at 06:14:38AM -0400, Brian Masney wrote:
> According to the downstream Android sources, the anx7808 variants use
> address 0x78 for TX_P0 and the anx781x variants use address 0x70. Since
> the datasheets aren't available for these devices, and we only have the
> downstream kernel sources to look at, let's assume that these addresses
> are fixed based on the model, and pass the i2c addresses to the data
> pointer in the driver's of_match_table.
> 
> Signed-off-by: Brian Masney <masneyb@...tation.org>
> ---
> V1 of this patch with some discussion:
> https://lore.kernel.org/lkml/20190815004854.19860-6-masneyb@onstation.org/
> 
>  drivers/gpu/drm/bridge/analogix-anx78xx.c | 36 +++++++++++++++--------
>  drivers/gpu/drm/bridge/analogix-anx78xx.h |  7 -----
>  2 files changed, 23 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/analogix-anx78xx.c b/drivers/gpu/drm/bridge/analogix-anx78xx.c
> index 48adf010816c..e25fae36dbe1 100644
> --- a/drivers/gpu/drm/bridge/analogix-anx78xx.c
> +++ b/drivers/gpu/drm/bridge/analogix-anx78xx.c
> @@ -38,12 +38,20 @@
>  #define AUX_CH_BUFFER_SIZE	16
>  #define AUX_WAIT_TIMEOUT_MS	15
>  
> -static const u8 anx78xx_i2c_addresses[] = {
> -	[I2C_IDX_TX_P0] = TX_P0,
> -	[I2C_IDX_TX_P1] = TX_P1,
> -	[I2C_IDX_TX_P2] = TX_P2,
> -	[I2C_IDX_RX_P0] = RX_P0,
> -	[I2C_IDX_RX_P1] = RX_P1,
> +static const u8 anx7808_i2c_addresses[] = {
> +	[I2C_IDX_TX_P0] = 0x78,
> +	[I2C_IDX_TX_P1] = 0x7a,
> +	[I2C_IDX_TX_P2] = 0x72,
> +	[I2C_IDX_RX_P0] = 0x7e,
> +	[I2C_IDX_RX_P1] = 0x80,
> +};
> +
> +static const u8 anx781x_i2c_addresses[] = {
> +	[I2C_IDX_TX_P0] = 0x70,
> +	[I2C_IDX_TX_P1] = 0x7a,
> +	[I2C_IDX_TX_P2] = 0x72,
> +	[I2C_IDX_RX_P0] = 0x7e,
> +	[I2C_IDX_RX_P1] = 0x80,
>  };

If those addresses are really fixed they should have been added to DT,
in order for all fixed I2C addresses used on an I2C bus to be reported
in DT. I guess it's too late now :-/ This seems to be the best we can do
to solve the problem with existing DT. Updating the bindings could
however still be a good idea to make this clear moving forward.

>  struct anx78xx_platform_data {
> @@ -1348,6 +1356,7 @@ static int anx78xx_i2c_probe(struct i2c_client *client,
>  	struct anx78xx *anx78xx;
>  	struct anx78xx_platform_data *pdata;
>  	unsigned int i, idl, idh, version;
> +	const u8 *i2c_addresses;
>  	bool found = false;
>  	int err;
>  
> @@ -1387,15 +1396,16 @@ static int anx78xx_i2c_probe(struct i2c_client *client,
>  	}
>  
>  	/* Map slave addresses of ANX7814 */
> +	i2c_addresses = device_get_match_data(&client->dev);
>  	for (i = 0; i < I2C_NUM_ADDRESSES; i++) {
>  		struct i2c_client *i2c_dummy;
>  
>  		i2c_dummy = i2c_new_dummy_device(client->adapter,
> -						 anx78xx_i2c_addresses[i] >> 1);
> +						 i2c_addresses[i] >> 1);
>  		if (IS_ERR(i2c_dummy)) {
>  			err = PTR_ERR(i2c_dummy);
>  			DRM_ERROR("Failed to reserve I2C bus %02x: %d\n",
> -				  anx78xx_i2c_addresses[i], err);
> +				  i2c_addresses[i], err);
>  			goto err_unregister_i2c;
>  		}
>  
> @@ -1405,7 +1415,7 @@ static int anx78xx_i2c_probe(struct i2c_client *client,
>  		if (IS_ERR(anx78xx->map[i])) {
>  			err = PTR_ERR(anx78xx->map[i]);
>  			DRM_ERROR("Failed regmap initialization %02x\n",
> -				  anx78xx_i2c_addresses[i]);
> +				  i2c_addresses[i]);
>  			goto err_unregister_i2c;
>  		}
>  	}
> @@ -1504,10 +1514,10 @@ MODULE_DEVICE_TABLE(i2c, anx78xx_id);
>  
>  #if IS_ENABLED(CONFIG_OF)
>  static const struct of_device_id anx78xx_match_table[] = {
> -	{ .compatible = "analogix,anx7808", },
> -	{ .compatible = "analogix,anx7812", },
> -	{ .compatible = "analogix,anx7814", },
> -	{ .compatible = "analogix,anx7818", },
> +	{ .compatible = "analogix,anx7808", .data = anx7808_i2c_addresses },
> +	{ .compatible = "analogix,anx7812", .data = anx781x_i2c_addresses },
> +	{ .compatible = "analogix,anx7814", .data = anx781x_i2c_addresses },
> +	{ .compatible = "analogix,anx7818", .data = anx781x_i2c_addresses },
>  	{ /* sentinel */ },
>  };
>  MODULE_DEVICE_TABLE(of, anx78xx_match_table);
> diff --git a/drivers/gpu/drm/bridge/analogix-anx78xx.h b/drivers/gpu/drm/bridge/analogix-anx78xx.h
> index 25e063bcecbc..8697647709f7 100644
> --- a/drivers/gpu/drm/bridge/analogix-anx78xx.h
> +++ b/drivers/gpu/drm/bridge/analogix-anx78xx.h
> @@ -6,13 +6,6 @@
>  #ifndef __ANX78xx_H
>  #define __ANX78xx_H
>  
> -#define TX_P0				0x70
> -#define TX_P1				0x7a
> -#define TX_P2				0x72
> -
> -#define RX_P0				0x7e
> -#define RX_P1				0x80
> -
>  /***************************************************************/
>  /* Register definition of device address 0x7e                  */
>  /***************************************************************/

Should you also rename the headers to mention [RT]X P[012] instead of
the numerical addresses ?

Apart from that,

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

-- 
Regards,

Laurent Pinchart