thr3ads.net - Nouveau - [PATCH RFC 1/4] drm/dp: Add helper to set LTTPRs in transparent mode [Nov 2024]

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Jani Nikula

2024-Nov-01 09:22 UTC

[PATCH RFC 1/4] drm/dp: Add helper to set LTTPRs in transparent mode

On Thu, 31 Oct 2024, Imre Deak <imre.deak at intel.com>
wrote:> On Thu, Oct 31, 2024 at 05:12:45PM +0200, Abel Vesa wrote:
>> According to the DisplayPort standard, LTTPRs have two operating
>> modes:
>>  - non-transparent - it replies to DPCD LTTPR field specific AUX
>>    requests, while passes through all other AUX requests
>>  - transparent - it passes through all AUX requests.
>> 
>> Switching between this two modes is done by the DPTX by issuing
>> an AUX write to the DPCD PHY_REPEATER_MODE register.
>> 
>> Add a generic helper that allows switching between these modes.
>> 
>> Signed-off-by: Abel Vesa <abel.vesa at linaro.org>
>> ---
>>  drivers/gpu/drm/display/drm_dp_helper.c | 17 +++++++++++++++++
>>  include/drm/display/drm_dp_helper.h     |  1 +
>>  2 files changed, 18 insertions(+)
>> 
>> diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
>> index
6ee51003de3ce616c3a52653c2f1979ad7658e21..38d612345986ad54b42228902ea718a089d169c4
100644
>> --- a/drivers/gpu/drm/display/drm_dp_helper.c
>> +++ b/drivers/gpu/drm/display/drm_dp_helper.c
>> @@ -2694,6 +2694,23 @@ int drm_dp_lttpr_max_link_rate(const u8
caps[DP_LTTPR_COMMON_CAP_SIZE])
>>  }
>>  EXPORT_SYMBOL(drm_dp_lttpr_max_link_rate);
>>  
>> +/**
>> + * drm_dp_lttpr_set_transparent_mode - set the LTTPR in transparent
mode
>> + * @aux: DisplayPort AUX channel
>> + * @enable: Enable or disable transparent mode
>> + *
>> + * Returns 0 on success or a negative error code on failure.
>
> Should be "Returns 1 on success".
But is that a sensible return value?
>
>> + */
>> +
Superfluous newline.
>> +int drm_dp_lttpr_set_transparent_mode(struct drm_dp_aux *aux, bool
enable)
>> +{
>> +	u8 val = enable ? DP_PHY_REPEATER_MODE_TRANSPARENT :
>> +			  DP_PHY_REPEATER_MODE_NON_TRANSPARENT;
>> +
>> +	return drm_dp_dpcd_writeb(aux, DP_PHY_REPEATER_MODE, val);
>> +}
>> +EXPORT_SYMBOL(drm_dp_lttpr_set_transparent_mode);
>> +
>>  /**
>>   * drm_dp_lttpr_max_lane_count - get the maximum lane count supported
by all LTTPRs
>>   * @caps: LTTPR common capabilities
>> diff --git a/include/drm/display/drm_dp_helper.h
b/include/drm/display/drm_dp_helper.h
>> index
279624833ea9259809428162f4e845654359f8c9..8821ab2d36b0e04d38ccbdddcb703b34de7ed680
100644
>> --- a/include/drm/display/drm_dp_helper.h
>> +++ b/include/drm/display/drm_dp_helper.h
>> @@ -625,6 +625,7 @@ int drm_dp_read_lttpr_phy_caps(struct drm_dp_aux
*aux,
>>  			       u8 caps[DP_LTTPR_PHY_CAP_SIZE]);
>>  int drm_dp_lttpr_count(const u8 cap[DP_LTTPR_COMMON_CAP_SIZE]);
>>  int drm_dp_lttpr_max_link_rate(const u8
caps[DP_LTTPR_COMMON_CAP_SIZE]);
>> +int drm_dp_lttpr_set_transparent_mode(struct drm_dp_aux *aux, bool
enable);
>>  int drm_dp_lttpr_max_lane_count(const u8
caps[DP_LTTPR_COMMON_CAP_SIZE]);
>>  bool drm_dp_lttpr_voltage_swing_level_3_supported(const u8
caps[DP_LTTPR_PHY_CAP_SIZE]);
>>  bool drm_dp_lttpr_pre_emphasis_level_3_supported(const u8
caps[DP_LTTPR_PHY_CAP_SIZE]);
>> 
>> -- 
>> 2.34.1
>> 
-- 
Jani Nikula, Intel

Imre Deak

2024-Nov-01 13:43 UTC

head link

[PATCH RFC 1/4] drm/dp: Add helper to set LTTPRs in transparent mode

On Fri, Nov 01, 2024 at 11:22:13AM +0200, Jani Nikula
wrote:> On Thu, 31 Oct 2024, Imre Deak <imre.deak at intel.com> wrote:
> > On Thu, Oct 31, 2024 at 05:12:45PM +0200, Abel Vesa wrote:
> >> According to the DisplayPort standard, LTTPRs have two operating
> >> modes:
> >>  - non-transparent - it replies to DPCD LTTPR field specific AUX
> >>    requests, while passes through all other AUX requests
> >>  - transparent - it passes through all AUX requests.
> >> 
> >> Switching between this two modes is done by the DPTX by issuing
> >> an AUX write to the DPCD PHY_REPEATER_MODE register.
> >> 
> >> Add a generic helper that allows switching between these modes.
> >> 
> >> Signed-off-by: Abel Vesa <abel.vesa at linaro.org>
> >> ---
> >>  drivers/gpu/drm/display/drm_dp_helper.c | 17 +++++++++++++++++
> >>  include/drm/display/drm_dp_helper.h     |  1 +
> >>  2 files changed, 18 insertions(+)
> >> 
> >> diff --git a/drivers/gpu/drm/display/drm_dp_helper.c
b/drivers/gpu/drm/display/drm_dp_helper.c
> >> index
6ee51003de3ce616c3a52653c2f1979ad7658e21..38d612345986ad54b42228902ea718a089d169c4
100644
> >> --- a/drivers/gpu/drm/display/drm_dp_helper.c
> >> +++ b/drivers/gpu/drm/display/drm_dp_helper.c
> >> @@ -2694,6 +2694,23 @@ int drm_dp_lttpr_max_link_rate(const u8
caps[DP_LTTPR_COMMON_CAP_SIZE])
> >>  }
> >>  EXPORT_SYMBOL(drm_dp_lttpr_max_link_rate);
> >>  
> >> +/**
> >> + * drm_dp_lttpr_set_transparent_mode - set the LTTPR in
transparent mode
> >> + * @aux: DisplayPort AUX channel
> >> + * @enable: Enable or disable transparent mode
> >> + *
> >> + * Returns 0 on success or a negative error code on failure.
> >
> > Should be "Returns 1 on success".
> 
> But is that a sensible return value?
It matches what the function returns, but yes, would make more sense to
fix the return value instead to be 0 in case of success.
> >
> >> + */
> >> +
> 
> Superfluous newline.
> 
> >> +int drm_dp_lttpr_set_transparent_mode(struct drm_dp_aux *aux,
bool enable)
> >> +{
> >> +	u8 val = enable ? DP_PHY_REPEATER_MODE_TRANSPARENT :
> >> +			  DP_PHY_REPEATER_MODE_NON_TRANSPARENT;
> >> +
> >> +	return drm_dp_dpcd_writeb(aux, DP_PHY_REPEATER_MODE, val);
> >> +}
> >> +EXPORT_SYMBOL(drm_dp_lttpr_set_transparent_mode);
> >> +
> >>  /**
> >>   * drm_dp_lttpr_max_lane_count - get the maximum lane count
supported by all LTTPRs
> >>   * @caps: LTTPR common capabilities
> >> diff --git a/include/drm/display/drm_dp_helper.h
b/include/drm/display/drm_dp_helper.h
> >> index
279624833ea9259809428162f4e845654359f8c9..8821ab2d36b0e04d38ccbdddcb703b34de7ed680
100644
> >> --- a/include/drm/display/drm_dp_helper.h
> >> +++ b/include/drm/display/drm_dp_helper.h
> >> @@ -625,6 +625,7 @@ int drm_dp_read_lttpr_phy_caps(struct
drm_dp_aux *aux,
> >>  			       u8 caps[DP_LTTPR_PHY_CAP_SIZE]);
> >>  int drm_dp_lttpr_count(const u8 cap[DP_LTTPR_COMMON_CAP_SIZE]);
> >>  int drm_dp_lttpr_max_link_rate(const u8
caps[DP_LTTPR_COMMON_CAP_SIZE]);
> >> +int drm_dp_lttpr_set_transparent_mode(struct drm_dp_aux *aux,
bool enable);
> >>  int drm_dp_lttpr_max_lane_count(const u8
caps[DP_LTTPR_COMMON_CAP_SIZE]);
> >>  bool drm_dp_lttpr_voltage_swing_level_3_supported(const u8
caps[DP_LTTPR_PHY_CAP_SIZE]);
> >>  bool drm_dp_lttpr_pre_emphasis_level_3_supported(const u8
caps[DP_LTTPR_PHY_CAP_SIZE]);
> >> 
> >> -- 
> >> 2.34.1
> >> 
> 
> -- 
> Jani Nikula, Intel

Nouveau - Nov 2024 - [PATCH RFC 1/4] drm/dp: Add helper to set LTTPRs in transparent mode

[PATCH RFC 1/4] drm/dp: Add helper to set LTTPRs in transparent mode

[PATCH RFC 1/4] drm/dp: Add helper to set LTTPRs in transparent mode