Re: [PATCH 08/12] drm: Add lspcon (custom type2 dp->hdmi) support

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On Mon, Apr 04, 2016 at 05:31:44PM +0530, Shashank Sharma wrote:
> This patch adds support for LSPCON devices in dp++ adaptor
> helper layer. LSPCON is DP++ type-2 adaptor with some customized
> functionalities, to provide additional features in Intel Gen9 HW.
> 
> LSPCON needs I2C-over-aux support to read/write control and
> data registers. This patch adds following:
>   - Functions for I2C over aux read/write
>   - Function to read EDID using I2c-over-aux
>   - Function to identify LSPCON among type-2 DP adaptors
> 
> Signed-off-by: Shashank Sharma <shashank.sharma@xxxxxxxxx>
> ---
>  drivers/gpu/drm/drm_dp_dual_mode_helper.c | 100 ++++++++++++++++++++++++++++++
>  include/drm/drm_dp_dual_mode_helper.h     |  10 +++
>  2 files changed, 110 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> index b72b7bb..ce8e11c 100644
> --- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> +++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
> @@ -132,6 +132,99 @@ ssize_t drm_dp_dual_mode_write(struct i2c_adapter *adapter,
>  }
>  EXPORT_SYMBOL(drm_dp_dual_mode_write);
>  
> +int drm_dp_dual_mode_get_edid(void *data,
> +	u8 *buf, unsigned int block, size_t len)
> +{
> +	struct i2c_adapter *adapter = data;
> +	unsigned char start = block * EDID_LENGTH;
> +	unsigned char segment = block >> 1;
> +	unsigned char xfers = segment ? 3 : 2;
> +	int ret, retries = 5;
> +
> +	do {
> +		struct i2c_msg msgs[] = {
> +			{
> +				.addr   = DP_DUAL_MODE_DDC_SEGMENT_ADDR,
> +				.flags  = 0,
> +				.len    = 1,
> +				.buf    = &segment,
> +			}, {
> +				.addr   = DDC_ADDR,
> +				.flags  = 0,
> +				.len    = 1,
> +				.buf    = &start,
> +			}, {
> +				.addr   = DDC_ADDR,
> +				.flags  = I2C_M_RD,
> +				.len    = len,
> +				.buf    = buf,
> +			}
> +		};
> +
> +		ret = adapter->algo->master_xfer(adapter, &msgs[3 - xfers],
> +						xfers);
> +
> +		if (ret == -ENXIO) {
> +			DRM_ERROR("Non-existent adapter %s\n",
> +				adapter->name);
> +			break;
> +		}
> +	} while (ret != xfers && --retries);
> +
> +	return ret == xfers ? 0 : -1;
> +}
> +EXPORT_SYMBOL(drm_dp_dual_mode_get_edid);

This sort of stuff shouldn't be needed. All that should be needed is
passing the right i2c adapter to drm_get_edid() and whatnot.

> +
> +/*
> +* drm_dp_dual_mode_ioa_xfer
> +* Few dp->hdmi type 2 adaptors allow i2c_over_aux read/write
> +* to the control and status registers. These functions help
> +* to read/write from those.
> +*/
> +static int drm_dp_dual_mode_ioa_xfer(struct i2c_adapter *adapter,
> +		u8 *buffer, u8 offset, u8 no_of_bytes, u8 rw_flag)
> +{
> +	int err = 0;
> +
> +	struct i2c_msg msgs[] = {
> +			{
> +				.addr	= DP_DUAL_MODE_SLAVE_ADDRESS,
> +				.flags	= 0,
> +				.len	= 1,
> +				.buf	= &offset,
> +			}, {
> +				.addr	= DP_DUAL_MODE_SLAVE_ADDRESS,
> +				.flags	= rw_flag,
> +				.len	= no_of_bytes,
> +				.buf	= buffer,
> +			}
> +	};
> +
> +	/* I2C over AUX here */
> +	err = adapter->algo->master_xfer(adapter, msgs, 2);
> +	if (err < 0)
> +		DRM_ERROR("LSPCON: Failed I2C over Aux read(addr=0x%x)\n",
> +				(unsigned int)offset);
> +
> +	return err;
> +}
> +
> +int drm_dp_dual_mode_ioa_read(struct i2c_adapter *adapter, u8 *buffer,
> +		u8 offset, u8 no_of_bytes)
> +{
> +	return drm_dp_dual_mode_ioa_xfer(adapter, buffer, offset,
> +		no_of_bytes, I2C_M_RD);
> +}
> +EXPORT_SYMBOL(drm_dp_dual_mode_ioa_read);
> +
> +int drm_dp_dual_mode_ioa_write(struct i2c_adapter *adapter, u8 *buffer,
> +		u8 offset, u8 no_of_bytes)
> +{
> +	return drm_dp_dual_mode_ioa_xfer(adapter, buffer, offset,
> +		no_of_bytes, 0);
> +}
> +EXPORT_SYMBOL(drm_dp_dual_mode_ioa_write);

Aren't these just dupes of the dual mode helper read/write functions?

> +
>  static bool is_hdmi_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN])
>  {
>  	static const char dp_dual_mode_hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN] =
> @@ -141,6 +234,11 @@ static bool is_hdmi_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN])
>  		      sizeof(dp_dual_mode_hdmi_id)) == 0;
>  }
>  
> +bool is_lspcon_adaptor(const uint8_t adaptor_id)
> +{
> +	return adaptor_id == 0xa8;
> +}
> +
>  /**
>   * drm_dp_dual_mode_detect - Identyfy the DP dual mode adaptor
>   * adapter: I2C adapter for the DDC bus
> @@ -197,6 +295,8 @@ enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter *adapter)
>  				    &adaptor_id, sizeof(adaptor_id));
>  	if (ret || (adaptor_id != (DP_DUAL_MODE_TYPE_TYPE2 |
>  				   DP_DUAL_MODE_REV_TYPE2))) {
> +		if (is_lspcon_adaptor(adaptor_id))
> +			return DRM_DP_DUAL_MODE_TYPE2_LSPCON;

We should reorganize this a bit I think. Probably should end up looking
somehting like:

bool is_type2_adaptor();
bool is_lspcon_adaptor();

if (ret == 0) {
	if (is_lspcon_adaptor())
		return TYPE2_LSPCON;
	else if (is_type2_adaptor() && is_hdmi_adaptor)
		return TYPE2_HDMI;
	else if (is_type2_adaptor())
		return TYPE2_DVI;
}

if (is_hdmi...)
	return TYPE1_HDMI;
else
	return TYPE1_DVI;


>  		if (is_hdmi_adaptor(hdmi_id))
>  			return DRM_DP_DUAL_MODE_TYPE1_HDMI;
>  		else
> diff --git a/include/drm/drm_dp_dual_mode_helper.h b/include/drm/drm_dp_dual_mode_helper.h
> index 8f8a8dc..26e3dd8 100644
> --- a/include/drm/drm_dp_dual_mode_helper.h
> +++ b/include/drm/drm_dp_dual_mode_helper.h
> @@ -24,6 +24,7 @@
>  #define DRM_DP_DUAL_MODE_HELPER_H
>  
>  #include <linux/types.h>
> +#include <drm/drm_edid.h>
>  
>  /*
>   * Optional for type 1 DVI adaptors
> @@ -55,6 +56,7 @@
>  #define  DP_DUAL_MODE_CEC_ENABLE 0x01
>  #define DP_DUAL_MODE_I2C_SPEED_CTRL 0x22
>  #define DP_DUAL_MODE_LAST_RESERVED 0xff
> +#define DP_DUAL_MODE_DDC_SEGMENT_ADDR 0x30
>  
>  struct i2c_adapter;
>  
> @@ -69,6 +71,7 @@ enum drm_dp_dual_mode_type {
>  	DRM_DP_DUAL_MODE_TYPE1_HDMI,
>  	DRM_DP_DUAL_MODE_TYPE2_DVI,
>  	DRM_DP_DUAL_MODE_TYPE2_HDMI,
> +	DRM_DP_DUAL_MODE_TYPE2_LSPCON,
>  };
>  
>  enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter *adapter);
> @@ -81,4 +84,11 @@ drm_dp_dual_mode_set_tmds_output(struct i2c_adapter *adapter, bool enable);
>  const char
>  *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type type);
>  
> +int drm_dp_dual_mode_ioa_read(struct i2c_adapter *adapter, u8 *buffer,
> +		u8 offset, u8 no_of_bytes);
> +int drm_dp_dual_mode_ioa_write(struct i2c_adapter *adapter, u8 *buffer,
> +		u8 offset, u8 no_of_bytes);
> +int drm_dp_dual_mode_get_edid(void *data,
> +	u8 *buf, unsigned int block, size_t len);
> +
>  #endif
> -- 
> 1.9.1

-- 
Ville Syrjälä
Intel OTC
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