Re: [PATCH v2 1/4] drm: Helper for lspcon in drm_dp_dual_mode

Rodrigo Vivi
2016-07-01T14:11:55Z

On Thu, Jun 30, 2016 at 10:58 PM, Sharma, Shashank
<shashank.sharma@intel.com> wrote:
> Thanks for the review Rodrigo. My comments inline.
>
> Regards
> Shashank
>
>
> On 7/1/2016 3:46 AM, Rodrigo Vivi wrote:
>>
>> On Tue, Jun 21, 2016 at 8:00 AM, Shashank Sharma
>> <shashank.sharma@intel.com> wrote:
>>>
>>> This patch adds lspcon support in dp_dual_mode helper.
>>> lspcon is essentially a dp->hdmi dongle with dual personality.
>>>
>>> LS mode: It works as a passive dongle, by level shifting DP++
>>> signals to HDMI signals, in LS mode.
>>> PCON mode: It works as a protocol converter active dongle
>>> in pcon mode, by converting DP++ outputs to HDMI 2.0 outputs.
>>>
>>> This patch adds support for lspcon detection and mode set
>>> switch operations, as a dp dual mode dongle.
>>>
>>> v2: Addressed review comments from Ville
>>> - add adaptor id for lspcon devices (0x08), use it to identify lspcon
>>> - change function names
>>> old: drm_lspcon_get_current_mode/drm_lspcon_change_mode
>>> new: drm_lspcon_get_mode/drm_lspcon_set_mode
>>> - change drm_lspcon_get_mode type to int, to match
>>> drm_dp_dual_mode_get_tmds_output
>>> - change 'err' to 'ret' to match the rest of the functions
>>> - remove pointless typecasting during call to dual_mode_read
>>> - fix the but while setting value of data, while writing lspcon mode
>>> - fix indentation
>>> - change mdelay(10) -> msleep(10)
>>> - return ETIMEDOUT instead of EFAULT, when lspcon mode change times out
>>> - Add an empty line to separate std regs macros and lspcon regs macros
>>> Indent bit definition
>>>
>>> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
>>> ---
>>> drivers/gpu/drm/drm_dp_dual_mode_helper.c | 103
>>> ++++++++++++++++++++++++++++++
>>> include/drm/drm_dp_dual_mode_helper.h | 25 ++++++++
>>> 2 files changed, 128 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>>> b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>>> index a7b2a75..404e715 100644
>>> --- a/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>>> +++ b/drivers/gpu/drm/drm_dp_dual_mode_helper.c
>>> @@ -148,6 +148,14 @@ static bool is_type2_adaptor(uint8_t adaptor_id)
>>> DP_DUAL_MODE_REV_TYPE2);
>>> }
>>>
>>> +bool is_lspcon_adaptor(const char hdmi_id[DP_DUAL_MODE_HDMI_ID_LEN],
>>> + const uint8_t adaptor_id)
>>> +{
>>> + return is_hdmi_adaptor(hdmi_id) &&
>>> + (adaptor_id == (DP_DUAL_MODE_REV_TYPE2 |
>>
>>
>> DP_DUAL_MODE_REV_TYPE2 = 0 so useless here and confusing.
>
> This was a review comment from Ville, on the last patch. I think he
> suggested for the better readability of the code.
>>
>>
>>> + DP_DUAL_MODE_TYPE_TYPE2 |
>>> DP_DUAL_MODE_TYPE_LSPCON));
>>
>>
>> Also this is confusing and took me a while to uderstand that LSPCON is
>> the type2 with DPCD
>
> I know, due to LSPCON's dual personality, its complicated to understand. I
> tried to cover some theory, in the cover letter, can add some here too:
> LSPCON is a dp->hdmi adapter which can operate in two modes
> Passive dongle mode / LS mode: in this mode, it acts as type2 dp dual mode
> adapter (no DPCD readable here)
> Active mode / PCON mode: in this mode, it acts as active DP++->HDMI2.0
> protocol convertor dongle, and allows DPCD read/write like a DP++ display.
>>
>>
>> so my suggestion is to define DP_DUAL_MODE_TYPE_HAS_DPCD (1<<3) with a
>> comment this is defined by LSPCON docs since this is not part of VESA
>> DP Dual Mode that only defines the Type2 = 0xA0.
>>
>> so you could use
>> TYPE2 | HAS_DPCD = LSPCON.
>>
> Sure, got it. Will change it like this.
>
>>> +}
>>> +
>>> /**
>>> * drm_dp_dual_mode_detect - Identify the DP dual mode adaptor
>>> * @adapter: I2C adapter for the DDC bus
>>> @@ -203,6 +211,8 @@ enum drm_dp_dual_mode_type
>>> drm_dp_dual_mode_detect(struct i2c_adapter *adapter)
>>> ret = drm_dp_dual_mode_read(adapter, DP_DUAL_MODE_ADAPTOR_ID,
>>> &adaptor_id, sizeof(adaptor_id));
>>> if (ret == 0) {
>>> + if (is_lspcon_adaptor(hdmi_id, adaptor_id))
>>> + return DRM_DP_DUAL_MODE_LSPCON;
>>> if (is_type2_adaptor(adaptor_id)) {
>>> if (is_hdmi_adaptor(hdmi_id))
>>> return DRM_DP_DUAL_MODE_TYPE2_HDMI;
>>> @@ -364,3 +374,96 @@ const char *drm_dp_get_dual_mode_type_name(enum
>>> drm_dp_dual_mode_type type)
>>> }
>>> }
>>> EXPORT_SYMBOL(drm_dp_get_dual_mode_type_name);
>>> +
>>> +/**
>>> + * drm_lspcon_get_current_mode: Get LSPCON's current mode of operation
>>> by
>>> + * by reading offset (0x80, 0x41)
>>> + * @i2c_adapter: I2C-over-aux adapter
>>> + * @current_mode: out vaiable, current lspcon mode of operation
>>> + *
>>> + * Returns:
>>> + * 0 on success, sets the current_mode value to appropriate mode
>>> + * -error on failure
>>> + */
>>> +int drm_lspcon_get_mode(struct i2c_adapter *adapter,
>>> + enum drm_lspcon_mode *current_mode)
>>> +{
>>> + u8 data;
>>> + int ret = 0;
>>> +
>>> + if (!current_mode) {
>>> + DRM_ERROR("NULL input\n");
>>> + return -EINVAL;
>>> + }
>>> +
>>> + /* Read Status: i2c over aux */
>>> + ret = drm_dp_dual_mode_read(adapter,
>>> DP_DUAL_MODE_LSPCON_CURRENT_MODE,
>>> + (void *)&data, sizeof(data));
>>> + if (ret < 0) {
>>> + DRM_ERROR("LSPCON read(0x80, 0x41) failed\n");
>>> + return -EFAULT;
>>> + }
>>
>>
>>> +
>>> + if (data & DP_DUAL_MODE_LSPCON_MODE_MASK)
>>> + *current_mode = DRM_LSPCON_MODE_PCON;
>>> + else
>>> + *current_mode = DRM_LSPCON_MODE_LS;
>>> + return 0;
>>> +}
>>> +EXPORT_SYMBOL(drm_lspcon_get_mode);
>>> +
>>> +/**
>>> + * drm_lspcon_change_mode: Change LSPCON's mode of operation by
>>> + * by writing offset (0x80, 0x40)
>>> + * @i2c_adapter: I2C-over-aux adapter
>>> + * @reqd_mode: required mode of operation
>>> + *
>>> + * Returns:
>>> + * 0 on success, -error on failure/timeout
>>> + */
>>> +int drm_lspcon_set_mode(struct i2c_adapter *adapter,
>>> + enum drm_lspcon_mode reqd_mode)
>>> +{
>>> + u8 data = 0;
>>> + int ret;
>>> + int time_out = 200;
>>> + enum drm_lspcon_mode changed_mode;
>>> +
>>> + if (reqd_mode == DRM_LSPCON_MODE_PCON)
>>> + data = DP_DUAL_MODE_LSPCON_MODE_MASK;
>>> +
>>> + /* Change mode */
>>> + ret = drm_dp_dual_mode_write(adapter,
>>> DP_DUAL_MODE_LSPCON_MODE_CHANGE,
>>> + &data, sizeof(data));
>>> + if (ret < 0) {
>>> + DRM_ERROR("LSPCON mode change failed\n");
>>> + return ret;
>>> + }
>>> +
>>> + /*
>>> + * Confirm mode change by reading the status bit.
>>> + * Sometimes, it takes a while to change the mode,
>>> + * so wait and retry until time out or done.
>>> + */
>>> + do {
>>> + ret = drm_lspcon_get_mode(adapter, &changed_mode);
>>> + if (ret) {
>>> + DRM_ERROR("cant confirm LSPCON mode change\n");
>>> + return ret;
>>> + } else {
>>> + if (changed_mode != reqd_mode) {
>>> + msleep(10);
>>> + time_out -= 10;
>>> + } else {
>>> + DRM_DEBUG_KMS("LSPCON mode changed to
>>> %s\n",
>>> + reqd_mode == DRM_LSPCON_MODE_LS ?
>>> + "LS" : "PCON");
>>> + return 0;
>>> + }
>>> + }
>>> + } while (time_out);
>>> +
>>> + DRM_ERROR("LSPCON mode change timed out\n");
>>> + return -ETIMEDOUT;
>>> +}
>>> +EXPORT_SYMBOL(drm_lspcon_set_mode);
>>> diff --git a/include/drm/drm_dp_dual_mode_helper.h
>>> b/include/drm/drm_dp_dual_mode_helper.h
>>> index e8a9dfd..441c6cb 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
>>> @@ -40,6 +41,7 @@
>>> #define DP_DUAL_MODE_REV_TYPE2 0x00
>>> #define DP_DUAL_MODE_TYPE_MASK 0xf0
>>> #define DP_DUAL_MODE_TYPE_TYPE2 0xa0
>>> +#define DP_DUAL_MODE_TYPE_LSPCON 0x08
>>> #define DP_DUAL_MODE_IEEE_OUI 0x11 /* 11-13*/
>>> #define DP_DUAL_IEEE_OUI_LEN 3
>>> #define DP_DUAL_DEVICE_ID 0x14 /* 14-19 */
>>> @@ -55,6 +57,10 @@
>>> #define DP_DUAL_MODE_CEC_ENABLE 0x01
>>> #define DP_DUAL_MODE_I2C_SPEED_CTRL 0x22
>>>
>>> +#define DP_DUAL_MODE_LSPCON_MODE_CHANGE 0x40
>>> +#define DP_DUAL_MODE_LSPCON_CURRENT_MODE 0x41
>>
>>
>> Where did you get this from? I haven't seen any offset 80, adress 41
>> defined anywhere in any of the docs I have here. What am I missing?
>>
> This offset was added by MCA after Intel requested them to confirm the
> LSPCON modeset success. Initially they gave us just 0x40, which is to
> request a change in mode from LS->PCON or other way. But we saw many times
> this change was not happening, so Intel requested MCA to have another
> register offset (0x41) to confirm the current LSPCON mode.
> I dont have an updated MCA doc on this, but I can arrange if you insist on
> this.

No, I won't insist. I take your world, but I believe it worth a
comment in the code explaining it in case some future reader find the
old spec we have.

>>>
>>> +#define DP_DUAL_MODE_LSPCON_MODE_MASK 0x1
>>
>>
>> I don't believe "mask" is a good term here....
>>
>> probably
>> DP_DUAL_MODE_LSPCON_MODE_PCON (1<<0)
>
> Agree, will change it to something as you suggested
>
> Shashank
>
>>
>>> +
>>> struct i2c_adapter;
>>>
>>> ssize_t drm_dp_dual_mode_read(struct i2c_adapter *adapter,
>>> @@ -63,6 +69,19 @@ ssize_t drm_dp_dual_mode_write(struct i2c_adapter
>>> *adapter,
>>> u8 offset, const void *buffer, size_t
>>> size);
>>>
>>> /**
>>> +* enum drm_lspcon_mode
>>> +* @lspcon_mode_ls: Level shifter mode of LSPCON
>>> +* which drives DP++ to HDMI 1.4 conversion.
>>> +* @lspcon_mode_pcon: Protocol converter mode of LSPCON
>>> +* which drives DP++ to HDMI 2.0 active conversion.
>>> +*/
>>> +enum drm_lspcon_mode {
>>> + DRM_LSPCON_MODE_INVALID,
>>> + DRM_LSPCON_MODE_LS,
>>> + DRM_LSPCON_MODE_PCON,
>>> +};
>>> +
>>> +/**
>>> * enum drm_dp_dual_mode_type - Type of the DP dual mode adaptor
>>> * @DRM_DP_DUAL_MODE_NONE: No DP dual mode adaptor
>>> * @DRM_DP_DUAL_MODE_UNKNOWN: Could be either none or type 1 DVI
>>> adaptor
>>> @@ -70,6 +89,7 @@ ssize_t drm_dp_dual_mode_write(struct i2c_adapter
>>> *adapter,
>>> * @DRM_DP_DUAL_MODE_TYPE1_HDMI: Type 1 HDMI adaptor
>>> * @DRM_DP_DUAL_MODE_TYPE2_DVI: Type 2 DVI adaptor
>>> * @DRM_DP_DUAL_MODE_TYPE2_HDMI: Type 2 HDMI adaptor
>>> + * @DRM_DP_DUAL_MODE_TYPE2_LSPCON: Level shifter /protocol converter
>>> */
>>> enum drm_dp_dual_mode_type {
>>> DRM_DP_DUAL_MODE_NONE,
>>> @@ -78,6 +98,7 @@ 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_LSPCON,
>>> };
>>>
>>> enum drm_dp_dual_mode_type drm_dp_dual_mode_detect(struct i2c_adapter
>>> *adapter);
>>> @@ -89,4 +110,8 @@ int drm_dp_dual_mode_set_tmds_output(enum
>>> drm_dp_dual_mode_type type,
>>> struct i2c_adapter *adapter, bool
>>> enable);
>>> const char *drm_dp_get_dual_mode_type_name(enum drm_dp_dual_mode_type
>>> type);
>>>
>>> +int drm_lspcon_get_mode(struct i2c_adapter *adapter,
>>> + enum drm_lspcon_mode *current_mode);
>>> +int drm_lspcon_set_mode(struct i2c_adapter *adapter,
>>> + enum drm_lspcon_mode reqd_mode);
>>> #endif
>>> --
>>> 1.9.1
>>>
>>> _______________________________________________
>>> Intel-gfx mailing list
>>> Intel-gfx@lists.freedesktop.org
>>> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>>
>>
>>
>>
>

--
Rodrigo Vivi
Blog: http://blog.vivi.eng.br