linux-kernel - Re: [PATCH v1 1/2] platform/x86: int3472: add hpd pin support

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Message-ID: <c8ae2d43-157c-408a-af89-7248b30d52d1@linux.intel.com>
Date: Mon, 14 Apr 2025 15:52:50 +0800
From: "Yan, Dongcheng" <dongcheng.yan@...ux.intel.com>
To: Hans de Goede <hdegoede@...hat.com>,
 Dongcheng Yan <dongcheng.yan@...el.com>, linux-kernel@...r.kernel.org,
 linux-media@...r.kernel.org, sakari.ailus@...ux.intel.com,
 hverkuil@...all.nl, andriy.shevchenko@...ux.intel.com,
 u.kleine-koenig@...libre.com, ricardo.ribalda@...il.com,
 bingbu.cao@...ux.intel.com
Cc: stable@...r.kernel.org, hao.yao@...el.com
Subject: Re: [PATCH v1 1/2] platform/x86: int3472: add hpd pin support

Hi hans,

On 4/11/2025 4:33 PM, Hans de Goede wrote:
> Hi,
> 
> On 11-Apr-25 10:23 AM, Dongcheng Yan wrote:
>> Typically HDMI to MIPI CSI-2 bridges have a pin to signal image data is
>> being received. On the host side this is wired to a GPIO for polling or
>> interrupts. This includes the Lontium HDMI to MIPI CSI-2 bridges
>> lt6911uxe and lt6911uxc.
>>
>> The GPIO "hpd" is used already by other HDMI to CSI-2 bridges, use it
>> here as well.
>>
>> Signed-off-by: Dongcheng Yan <dongcheng.yan@...el.com>
>> ---
>>  drivers/platform/x86/intel/int3472/common.h   | 1 +
>>  drivers/platform/x86/intel/int3472/discrete.c | 6 ++++++
>>  2 files changed, 7 insertions(+)
>>
>> diff --git a/drivers/platform/x86/intel/int3472/common.h b/drivers/platform/x86/intel/int3472/common.h
>> index 145dec66df64..db4cd3720e24 100644
>> --- a/drivers/platform/x86/intel/int3472/common.h
>> +++ b/drivers/platform/x86/intel/int3472/common.h
>> @@ -22,6 +22,7 @@
>>  #define INT3472_GPIO_TYPE_POWER_ENABLE				0x0b
>>  #define INT3472_GPIO_TYPE_CLK_ENABLE				0x0c
>>  #define INT3472_GPIO_TYPE_PRIVACY_LED				0x0d
>> +#define INT3472_GPIO_TYPE_HOTPLUG_DETECT			0x13
>>  
>>  #define INT3472_PDEV_MAX_NAME_LEN				23
>>  #define INT3472_MAX_SENSOR_GPIOS				3
>> diff --git a/drivers/platform/x86/intel/int3472/discrete.c b/drivers/platform/x86/intel/int3472/discrete.c
>> index 30ff8f3ea1f5..28d41b1b3809 100644
>> --- a/drivers/platform/x86/intel/int3472/discrete.c
>> +++ b/drivers/platform/x86/intel/int3472/discrete.c
>> @@ -186,6 +186,10 @@ static void int3472_get_con_id_and_polarity(struct acpi_device *adev, u8 *type,
>>  		*con_id = "privacy-led";
>>  		*gpio_flags = GPIO_ACTIVE_HIGH;
>>  		break;
>> +	case INT3472_GPIO_TYPE_HOTPLUG_DETECT:
>> +		*con_id = "hpd";
>> +		*gpio_flags = GPIO_LOOKUP_FLAGS_DEFAULT;
> 
> This looks wrong, we really need to clearly provide a polarity
> here since the ACPI GPIO resources do not provide one.
> 
I tested gpio_flags=GPIO_LOOKUP_FLAGS_DEFAULT/HIGH/LOW, the lt6911uxe
driver can pass the test and work normally. Is this the rule of int3472
driver?
In addition, GPIO_LOOKUP_FLAGS_DEFAULT	= GPIO_ACTIVE_HIGH |
GPIO_PERSISTENT as defined, maybe it provides a polarity also.
I can change to GPIO_ACTIVE_LOW, but I want to understand the reason.

Best Regard,
Dongcheng> Regards,
> 
> Hans
> 
> 
> 
>> +		break;
>>  	case INT3472_GPIO_TYPE_POWER_ENABLE:
>>  		*con_id = "power-enable";
>>  		*gpio_flags = GPIO_ACTIVE_HIGH;
>> @@ -212,6 +216,7 @@ static void int3472_get_con_id_and_polarity(struct acpi_device *adev, u8 *type,
>>   * 0x0b Power enable
>>   * 0x0c Clock enable
>>   * 0x0d Privacy LED
>> + * 0x13 Hotplug detect
>>   *
>>   * There are some known platform specific quirks where that does not quite
>>   * hold up; for example where a pin with type 0x01 (Power down) is mapped to
>> @@ -281,6 +286,7 @@ static int skl_int3472_handle_gpio_resources(struct acpi_resource *ares,
>>  	switch (type) {
>>  	case INT3472_GPIO_TYPE_RESET:
>>  	case INT3472_GPIO_TYPE_POWERDOWN:
>> +	case INT3472_GPIO_TYPE_HOTPLUG_DETECT:
>>  		ret = skl_int3472_map_gpio_to_sensor(int3472, agpio, con_id, gpio_flags);
>>  		if (ret)
>>  			err_msg = "Failed to map GPIO pin to sensor\n";
>>
>> base-commit: 01c6df60d5d4ae00cd5c1648818744838bba7763
> 
>