[PATCH] drm: bridge: dw-hdmi: support i2c extended read mode

Wed Feb 22 03:11:09 PST 2017

Hi Jose,

在 2017年02月22日 17:51, Jose Abreu 写道:
> Hi Nickey,
>
>
> On 22-02-2017 07:45, Nickey Yang wrote:
>> "I2C Master Interface Extended Read Mode" implements a segment
>> pointer-based read operation using the Special Register configuration.
>>
>> This patch fix https://urldefense.proofpoint.com/v2/url?u=https-3A__patchwork.kernel.org_patch_7098101_&d=DwIBAg&c=DPL6_X_6JkXFx7AXWqB0tg&r=yaVFU4TjGY0gVF8El1uKcisy6TPsyCl9uN7Wsis-qhY&m=GO5hTo1pTsXMTs-_YDONdmAGQyk8vf0XXA5s-P77fPo&s=cy1I1t3kDvC0ihSnmEqbDx-PiPvzXaksyM9G240RSmE&e=  mentioned
>> "The current implementation does not support "I2C Master Interface
>> Extended Read Mode" to read data addressed by non-zero segment
>> pointer, this means that if EDID has more than 1 extension blocks"
>>
>> With this patch,dw-hdmi can read EDID data with 1/2/4 blocks.
> Can't read an EDID with 3 extension blocks? Why? (I'm not reading
> the spec so I don't know if this is possible to exist. Maybe only
> an even number of blocks is allowed).
>
Read EDID func is drm_do_probe_ddc_edid    (in 
drivers/gpu/drm/drm_edid.c     Line:1215)
when block = 3  means &msgs[3].addr = DDC_SEGMENT_ADDR(0x30) ,but in 
dw_hdmi_i2c_xfer
line 299  msgs[i].addr != addr (0x50),  it will printk "unsupported 
transfer, changed slave address"
and return -EOPNOTSUPP.

in fact,0x30 not means change slave address but means segment address.

>> Signed-off-by: Nickey Yang <nickey.yang at rock-chips.com>
>> ---
>>   drivers/gpu/drm/bridge/dw-hdmi.c | 38 ++++++++++++++++++++++++--------------
>>   1 file changed, 24 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c
>> index 9a9ec27..6ad7b87 100644
>> --- a/drivers/gpu/drm/bridge/dw-hdmi.c
>> +++ b/drivers/gpu/drm/bridge/dw-hdmi.c
>> @@ -33,6 +33,7 @@
>>   #include "dw-hdmi-audio.h"
>>   
>>   #define HDMI_EDID_LEN		512
>> +#define DDC_SEGMENT_ADDR       0x30
>>   
>>   #define RGB			0
>>   #define YCBCR444		1
>> @@ -111,6 +112,7 @@ struct dw_hdmi_i2c {
>>   
>>   	u8			slave_reg;
>>   	bool			is_regaddr;
>> +	bool			is_segment;
>>   };
>>   
>>   struct dw_hdmi_phy_data {
>> @@ -258,8 +260,12 @@ static int dw_hdmi_i2c_read(struct dw_hdmi *hdmi,
>>   		reinit_completion(&i2c->cmp);
>>   
>>   		hdmi_writeb(hdmi, i2c->slave_reg++, HDMI_I2CM_ADDRESS);
>> -		hdmi_writeb(hdmi, HDMI_I2CM_OPERATION_READ,
>> -			    HDMI_I2CM_OPERATION);
>> +		if (i2c->is_segment)
>> +			hdmi_writeb(hdmi, HDMI_I2CM_OPERATION_READ_EXT,
>> +				    HDMI_I2CM_OPERATION);
>> +		else
>> +			hdmi_writeb(hdmi, HDMI_I2CM_OPERATION_READ,
>> +				    HDMI_I2CM_OPERATION);
>>   
>>   		stat = wait_for_completion_timeout(&i2c->cmp, HZ / 10);
>>   		if (!stat)
>> @@ -271,6 +277,7 @@ static int dw_hdmi_i2c_read(struct dw_hdmi *hdmi,
>>   
>>   		*buf++ = hdmi_readb(hdmi, HDMI_I2CM_DATAI);
>>   	}
>> +	i2c->is_segment = false;
>>   
>>   	return 0;
>>   }
>> @@ -320,12 +327,6 @@ static int dw_hdmi_i2c_xfer(struct i2c_adapter *adap,
>>   	dev_dbg(hdmi->dev, "xfer: num: %d, addr: %#x\n", num, addr);
>>   
>>   	for (i = 0; i < num; i++) {
>> -		if (msgs[i].addr != addr) {
>> -			dev_warn(hdmi->dev,
>> -				 "unsupported transfer, changed slave address\n");
>> -			return -EOPNOTSUPP;
>> -		}
>> -
>>   		if (msgs[i].len == 0) {
>>   			dev_dbg(hdmi->dev,
>>   				"unsupported transfer %d/%d, no data\n",
>> @@ -345,15 +346,24 @@ static int dw_hdmi_i2c_xfer(struct i2c_adapter *adap,
>>   	/* Set slave device register address on transfer */
>>   	i2c->is_regaddr = false;
>>   
>> +	/* Set segment pointer for I2C extended read mode operation */
>> +	i2c->is_segment = false;
>> +
>>   	for (i = 0; i < num; i++) {
>>   		dev_dbg(hdmi->dev, "xfer: num: %d/%d, len: %d, flags: %#x\n",
>>   			i + 1, num, msgs[i].len, msgs[i].flags);
>> -
>> -		if (msgs[i].flags & I2C_M_RD)
>> -			ret = dw_hdmi_i2c_read(hdmi, msgs[i].buf, msgs[i].len);
>> -		else
>> -			ret = dw_hdmi_i2c_write(hdmi, msgs[i].buf, msgs[i].len);
>> -
>> +		if (msgs[i].addr == DDC_SEGMENT_ADDR && msgs[i].len == 1) {
>> +			i2c->is_segment = true;
>> +			hdmi_writeb(hdmi, DDC_SEGMENT_ADDR, HDMI_I2CM_SEGADDR);
>> +			hdmi_writeb(hdmi, *msgs[i].buf, HDMI_I2CM_SEGPTR);
> Hmm, this does not match what I have here internally but I may
> have something wrong. You tested this using an EDID with how many
> extension blocks?
>
> Anyway, this is what I have:
>      if(msgs[i].addr == DDC_SEGMENT_ADDR && msgs[i].len == 1) {
>          hdmi_writeb(hdmi, msgs[i].buf[0], HDMI_I2CM_SEGADDR);
>          [and segptr is 0x0]
>      }
>
> I probably may have something wrong but I remember I tested this
> a long time ago using an HDMI 2.0 EDID and it worked fine. BUT, I
> have special cases for other addresses (0x50 and 0x54), I can't
> remember if these are for EDID or for SCDC. I can send you the
> code I have if you want.
>
> Best regards,
> Jose Miguel Abreu
>
I have tested this using an EDID with 0/1/3 extension blocks including HDMI1.4/2.0 EDID.
We pass HDMI CDF certification  successfully with this.
(  Test  Item 7-1:  EDID Related Behavior  2-Block EDID , 4-Block EDID)

0x50  is ddc slave address for read edid.
0x54  is ddc slave address for scdc operation.
0x30 is ddc  segment address.
(segaddr
This register configures the segment address for extended R/W destination and is used for EDID reading
operations, particularly for the Extended Data Read Operation for Enhanced DDC)

Best regards,
Nickey Yang

>> +		} else {
>> +			if (msgs[i].flags & I2C_M_RD)
>> +				ret = dw_hdmi_i2c_read(hdmi, msgs[i].buf,
>> +						       msgs[i].len);
>> +			else
>> +				ret = dw_hdmi_i2c_write(hdmi, msgs[i].buf,
>> +							msgs[i].len);
>> +		}
>>   		if (ret < 0)
>>   			break;
>>   	}
>
>
>