Re: [Intel-gfx] [PATCH] drm/i915/dsi: Lookup the i2c bus from ACPI NS only if CONFIG_ACPI=y (v3)

[Jani Nikula <jani.nikula@intel.com>]

On Wed, 15 Jan 2020, Vivek Kasireddy <vivek.kasireddy@intel.com> wrote:
> Perform the i2c bus/adapter lookup from ACPI Namespace only if
> ACPI is enabled in the kernel config. If ACPI is not enabled or if
> the lookup fails, we'll fallback to using the VBT for identiying
> the i2c bus.
>
> v2: Clearly identify the commit this patch is fixing (Jani)
>
> v3: Remove the i2c_bus_num >= 0 check from the adapter lookup function
> as this would prevent ACPI bus number override. This check was mainly
> there to return early if the bus number has already been found but we
> anyway return in the next line if the slave address does not match.
>
> Fixes: 8cbf89db2941 ("drm/i915/dsi: Parse the I2C element from the VBT MIPI sequence block (v3)")
> Cc: Hans de Goede <hdegoede@redhat.com>
> Cc: Nabendu Maiti <nabendu.bikash.maiti@intel.com>
> Cc: Matt Roper <matthew.d.roper@intel.com>
> Cc: Bob Paauwe <bob.j.paauwe@intel.com>
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dsi_vbt.c | 50 +++++++++++++-------
>  1 file changed, 32 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dsi_vbt.c b/drivers/gpu/drm/i915/display/intel_dsi_vbt.c
> index 89fb0d90b694..04f953ba8f00 100644
> --- a/drivers/gpu/drm/i915/display/intel_dsi_vbt.c
> +++ b/drivers/gpu/drm/i915/display/intel_dsi_vbt.c
> @@ -384,6 +384,7 @@ static const u8 *mipi_exec_gpio(struct intel_dsi *intel_dsi, const u8 *data)
>  	return data;
>  }
>  
> +#ifdef CONFIG_ACPI
>  static int i2c_adapter_lookup(struct acpi_resource *ares, void *data)
>  {
>  	struct i2c_adapter_lookup *lookup = data;
> @@ -393,8 +394,7 @@ static int i2c_adapter_lookup(struct acpi_resource *ares, void *data)
>  	acpi_handle adapter_handle;
>  	acpi_status status;
>  
> -	if (intel_dsi->i2c_bus_num >= 0 ||
> -	    !i2c_acpi_get_i2c_resource(ares, &sb))
> +	if (!i2c_acpi_get_i2c_resource(ares, &sb))
>  		return 1;

The above hunk turns v3 of the patch from a straightforward build fix
into a functional change. They *must* be separate.

I've pushed v2 into drm-intel-next-queued, please send the above change
as a standalone fix that it rightly is, with its own commit message and
rationale.

BR,
Jani.



>  
>  	if (lookup->slave_addr != sb->slave_address)
> @@ -413,14 +413,41 @@ static int i2c_adapter_lookup(struct acpi_resource *ares, void *data)
>  	return 1;
>  }
>  
> -static const u8 *mipi_exec_i2c(struct intel_dsi *intel_dsi, const u8 *data)
> +static void i2c_acpi_find_adapter(struct intel_dsi *intel_dsi,
> +				  const u16 slave_addr)
>  {
>  	struct drm_device *drm_dev = intel_dsi->base.base.dev;
>  	struct device *dev = &drm_dev->pdev->dev;
> -	struct i2c_adapter *adapter;
>  	struct acpi_device *acpi_dev;
>  	struct list_head resource_list;
>  	struct i2c_adapter_lookup lookup;
> +
> +	acpi_dev = ACPI_COMPANION(dev);
> +	if (acpi_dev) {
> +		memset(&lookup, 0, sizeof(lookup));
> +		lookup.slave_addr = slave_addr;
> +		lookup.intel_dsi = intel_dsi;
> +		lookup.dev_handle = acpi_device_handle(acpi_dev);
> +
> +		INIT_LIST_HEAD(&resource_list);
> +		acpi_dev_get_resources(acpi_dev, &resource_list,
> +				       i2c_adapter_lookup,
> +				       &lookup);
> +		acpi_dev_free_resource_list(&resource_list);
> +	}
> +}
> +#else
> +static inline void i2c_acpi_find_adapter(struct intel_dsi *intel_dsi,
> +					 const u16 slave_addr)
> +{
> +}
> +#endif
> +
> +static const u8 *mipi_exec_i2c(struct intel_dsi *intel_dsi, const u8 *data)
> +{
> +	struct drm_device *drm_dev = intel_dsi->base.base.dev;
> +	struct device *dev = &drm_dev->pdev->dev;
> +	struct i2c_adapter *adapter;
>  	struct i2c_msg msg;
>  	int ret;
>  	u8 vbt_i2c_bus_num = *(data + 2);
> @@ -431,20 +458,7 @@ static const u8 *mipi_exec_i2c(struct intel_dsi *intel_dsi, const u8 *data)
>  
>  	if (intel_dsi->i2c_bus_num < 0) {
>  		intel_dsi->i2c_bus_num = vbt_i2c_bus_num;
> -
> -		acpi_dev = ACPI_COMPANION(dev);
> -		if (acpi_dev) {
> -			memset(&lookup, 0, sizeof(lookup));
> -			lookup.slave_addr = slave_addr;
> -			lookup.intel_dsi = intel_dsi;
> -			lookup.dev_handle = acpi_device_handle(acpi_dev);
> -
> -			INIT_LIST_HEAD(&resource_list);
> -			acpi_dev_get_resources(acpi_dev, &resource_list,
> -					       i2c_adapter_lookup,
> -					       &lookup);
> -			acpi_dev_free_resource_list(&resource_list);
> -		}
> +		i2c_acpi_find_adapter(intel_dsi, slave_addr);
>  	}
>  
>  	adapter = i2c_get_adapter(intel_dsi->i2c_bus_num);

-- 
Jani Nikula, Intel Open Source Graphics Center
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