[PATCH 2/2] efi_loader: fix device-path for USB devices

[Heinrich Schuchardt]

On 3/20/23 19:39, Simon Glass wrote:
> Hi Heinrich,
> 
> On Mon, 20 Mar 2023 at 09:58, Heinrich Schuchardt
> <heinrich.schuchardt at canonical.com> wrote:
>>
>>
>>
>> On 3/19/23 20:29, Simon Glass wrote:
>>> Hi Heinrich,
>>>
>>> On Mon, 20 Mar 2023 at 04:25, Heinrich Schuchardt
>>> <heinrich.schuchardt at canonical.com> wrote:
>>>>
>>>> EFI device paths for block devices must be unique. If a non-unique device
>>>> path is discovered, probing of the block device fails.
>>>>
>>>> Currently we use UsbClass() device path nodes. As multiple devices may
>>>> have the same vendor and product id these are non-unique. Instead we
>>>> should use Usb() device path nodes. They include the USB port on the
>>>> parent hub. Hence they are unique.
>>>>
>>>> A USB storage device may contain multiple logical units. These can be
>>>> modeled as Ctrl() nodes.
>>>>
>>>> Reported-by: Patrick Delaunay <patrick.delaunay at foss.st.com>
>>>> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
>>>> ---
>>>>    lib/efi_loader/efi_device_path.c | 45 +++++++++++++++++++++++---------
>>>>    1 file changed, 33 insertions(+), 12 deletions(-)
>>>
>>> Reviewed-by: Simon Glass <sjg at chromium.org>
>>>
>>> [..]
>>>
>>>>
>>>> diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
>>>> index 3b267b713e..b6dd575b13 100644
>>>> --- a/lib/efi_loader/efi_device_path.c
>>>> +++ b/lib/efi_loader/efi_device_path.c
>>>> @@ -147,7 +147,7 @@ struct efi_device_path *efi_dp_shorten(struct efi_device_path *dp)
>>>>                    * in practice fallback.efi just uses MEDIA:HARD_DRIVE
>>>>                    * so not sure when we would see these other cases.
>>>>                    */
>>>> -               if (EFI_DP_TYPE(dp, MESSAGING_DEVICE, MSG_USB_CLASS) ||
>>>> +               if (EFI_DP_TYPE(dp, MESSAGING_DEVICE, MSG_USB) ||
>>>>                       EFI_DP_TYPE(dp, MEDIA_DEVICE, HARD_DRIVE_PATH) ||
>>>>                       EFI_DP_TYPE(dp, MEDIA_DEVICE, FILE_PATH))
>>>>                           return dp;
>>>> @@ -564,6 +564,11 @@ __maybe_unused static unsigned int dp_size(struct udevice *dev)
>>>>                           return dp_size(dev->parent)
>>>>                                   + sizeof(struct efi_device_path_vendor) + 1;
>>>>    #endif
>>>> +#ifdef CONFIG_USB
>>>> +               case UCLASS_MASS_STORAGE:
>>>
>>> Can we do:
>>>
>>>                  case UCLASS_MASS_STORAGE:
>>>                     if (IS_ENABLED(CONFIG_USB)) {
>>>                              ...
>>>                     }
>>>
>>> ?
>>
>> That should be possible too. Didn't you want to get rid of IS_ENABLED()?
>> CONFIG_IS_ENABLED() would work here too.
> 
> I was wanting to get rid of CONFIG_IS_ENABLED() for things that don't
> have an SPL Kconfig, then eventually get rid of CONFIG_IS_ENABLED().
> I've got a bit lost in all the problems though.
> 
>>
>> The whole way that we create device paths is not consistent. We should
>> have a device path node for each DM device.
>>
>> With v2023.07 I want to add
>>
>>       struct efi_device_path *(*get_dp_node)(struct udevice *dev);
>>
>> to struct uclass_driver and move the generation of device path nodes to
>> the individual uclass drivers.
> 
> We could also send an event (EVT_EFI_GET_DP_NODE) and connect it that
> way...ie would add less space to driver model. But yes it would be
> good to line up EFI and DM a bit better.

The type of device-path node to be created is uclass specific:

For an NVMe device we will always create a NVMe() node.
For a block device we will always create a Ctrl() node with the LUN number.
...

For drivers that don't implement the method yet we can create a VenHw() 
node per default with uclass-id and device number encoded in the node.

You suggested yourself that the DM and the EFI implementation should be 
tightly integrated.

I cannot see what the use of an event should be. Why should each udevice 
register to an event when all we need is a simple function like:

#if CONFIG_IS_ENABLED(EFI_LOADER)
struct efi_device_path *uclass_get_dp_node(struct udevice *dev)
{
        struct uclass *uc;
        struct efi_device_path_uboot *dp;

        uc = dev->uclass;
        if (uc->uc_drv->get_dp_node)
                return uc->uc_drv->get_dp_node(dev);

        dp = efi_alloc(sizeof(struct efi_device_path_uboot));
        if (!dp)
                return NULL;

        dp->dp.type = DEVICE_PATH_TYPE_HARDWARE_DEVICE;
        dp->dp.sub_type = DEVICE_PATH_SUB_TYPE_VENDOR;
        dp->dp.length = sizeof(struct efi_device_path_uboot);
        dp->guid = efi_u_boot_guid;
        dp->uclass_id = uc->uc_drv->id;
        dp->seq_ = dev->seq_;

        return &dp->dp;
}
#endif

Best regards

Heinrich