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

["Sharma, Shashank" <shashank.sharma@intel.com>]

Regards
Shashank

On 5/2/2016 7:19 PM, Ville Syrjälä wrote:
> 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@intel.com>
>> ---
>>   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.
>
Yeah, agree, we can optimize this.
>> +
>> +/*
>> +* 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?
No, I2C over aux read uses adapter->algo->master_xfer function, which is 
different in case of aux channel read/write. dp_dual_mode uses i2c_xfer.
>
>> +
>>   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;
>
>
Yep, this is a good suggestion.
>>   		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
>
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