tud_msc_write10_cb and other msc function is no longer weak (IEC-426)

[qwx]

Answers checklist.

• I have read the documentation of the component in question and the issue is not addressed there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

General issue report

I upgrad my esp-usb from 1.x to 2.x, I found some function like tud_msc_write10_cb and tud_msc_read10_cb no longer have TU_ATTR_WEAK.
My program use these function to overridder some default beheaver to do some work like remap a file to a msc device or change vid pid rev in tud_msc_inquiry_cb.
so is there a right way to do this?
Thanks a lot.

[github-actions]

Hi @qwx! Please be aware that the following suggestions are generated by a bot and haven't been fact-checked by Espressif Systems. We hope that this message will help you until an Espressif Engineer looks at your issue.

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In esp-usb 2.x (esp_tinyusb v2.x), the MSC API was intentionally redesigned and the old per-command weak callbacks like tud_msc_write10_cb, tud_msc_read10_cb, tud_msc_inquiry_cb, etc. were removed from the Espressif layer in favor of a single event‑based callback per storage. [esp_tinyusb 2.0.0]

From the release notes:

• MSC: Removed dedicated callbacks; introduced a single callback with an event ID for each storage
• MSC: Added storage format support
• MSC: Added dual storage support (SPI/Flash and SD/MMC)
• MSC: Updated public API; refer to the MSC Class Migration guide v2 [esp_tinyusb 2.0.0]

So:

• The behavior you relied on (overriding tud_msc_* weak functions directly) is no longer the supported integration method in v2.x.
• The “right way” in esp-usb 2.x is to:
  • Register the MSC storage(s) using the new esp_tinyusb MSC API, and
  • Implement your custom behavior (remapping files, changing VID/PID/revision, etc.) inside the single MSC callback that receives an event ID and associated data for each operation.

Unfortunately, the detailed MSC v2 API and the “MSC Class Migration guide v2” are only referenced in the release notes and not included in the provided sources, so I cannot quote exact function names or enums. The migration guide linked in the release notes should show:

• How to register the MSC storage(s),
• The prototype of the unified MSC callback, and
• Which event IDs correspond to operations that previously used tud_msc_write10_cb, tud_msc_read10_cb, tud_msc_inquiry_cb, etc., and how to customize the INQUIRY data (VID/PID/REV) there. [esp_tinyusb 2.0.0]

In summary: in esp-usb 2.x you should stop overriding TinyUSB’s tud_msc_* weak functions directly and instead implement your logic in the new esp_tinyusb MSC event callback as described in the MSC Class Migration guide v2.

[qwx]

so I read bot's suggestions and review the code, but i still can't find right way to do this(e.g. change vid pid rev in tud_msc_inquiry_cb). Or I should disable MSC and use my own app MSC driver?

[roma-jam]

Hi @qwx,

thanks for the report and bot comment isn't applicable here, you are right. Sorry for the inconvenience.

Regarding the tud_msc_inquiry_cb, only the data has changed, not the attribute.
So, if you are using the MSC class from the driver (CONFIG_TINYUSB_MSC_ENABLED=y), these function should be implemented and there is no way to override the callbacks, such as mentioned above.

We didn't have the option to customize the data, returning during the INQUIRY in the esp_tinyusb v1.x and we still do not have it right now with esp_tinyusb v2.x, but we can consider adding such feature in the future release.

Could you please specify your case a bit more so we can proceed with its' implementation?

[qwx]

Hi @qwx,

thanks for the report and bot comment isn't applicable here, you are right. Sorry for the inconvenience.

Regarding the tud_msc_inquiry_cb, only the data has changed, not the attribute. So, if you are using the MSC class from the driver (CONFIG_TINYUSB_MSC_ENABLED=y), these function should be implemented and there is no way to override the callbacks, such as mentioned above.

We didn't have the option to customize the data, returning during the INQUIRY in the esp_tinyusb v1.x and we still do not have it right now with esp_tinyusb v2.x, but we can consider adding such feature in the future release.

Could you please specify your case a bit more so we can proceed with its' implementation?

@roma-jam
Thank you very much for your prompt reply！
Sometimes we don't want to modify the overall structure of the callback functions, such as when tud_msc_read10_cb should be called, but rather just ensure that this function is invoked at the appropriate time as expected. For example, in our program, we override only the tud_msc_read10_cb function instead of replacing the entire MSC callback. It's often difficult for people to understand exactly when tud_msc_read10_cb and tud_msc_write10_cb should be triggered, but it's much easier to grasp what these functions do and customize them accordingly. In our case, tud_msc_read10_cb does not read from a physical disk but instead retrieves data from a file content, so we have overridden tud_msc_read10_cb to reflect this behavior. Without the use of weak symbols, we would be forced to rewrite all functions starting from the MSC driver level, rather than simply redefining tud_msc_read10_cb and the callback responsible for retrieving disk parameters. Regarding the tud_msc_inquiry_cb function you mentioned, it’s true that certain configurations could handle such cases. Hopefully, future enhancements will provide more flexible configuration options allowing users greater freedom in customization.

Sorry about english, I use ai to translate from another language.

[roma-jam]

Hi @qwx,

let me try to clarify couple of details to understand the problem better.

I upgrad my esp-usb from 1.x to 2.x, I found some function like tud_msc_write10_cb and tud_msc_read10_cb no longer have TU_ATTR_WEAK.

They were also implemented in tusb_msc_storage.c in the version 1.x and there was no option to override them. This didn't change in the version 2.x: if you use the storage api, then everything else is handled in the driver.

This was made intentionally, because in both versions the storage might be or SPIFLASH or SDMMC, and there are no other options available.

My program use these function to overridder some default beheaver to do some work like remap a file to a msc device or change vid pid rev in tud_msc_inquiry_cb.

There are no VID/PID in the INQUIRY callback.
If you need to change the VID/PID, you can provide them during driver installation, by assigning custom device descriptor.
Please, refer to the snippets from here: https://github.com/espressif/esp-usb/blob/master/device/esp_tinyusb/README.md#usb-descriptors-configuration

Please let me know whether it helps or you have any other questions.

I will keep this open, because soon we might add the feature to customize the INQUIRY data during the storage creation.