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Hello,
This question is related to the below my post.
https://e2e.ti.com/support/interface/f/138/p/825259/3053028
At first, I’m very sorry, the part number was wrong. It was not TUSB4020 but TUSB8041.
While the customer is also contacting to the IC vender for SD/MMC controller IC, they found it could be solved by changing Device Removable Configuration Register of TUSB8041 to “Not Removable” for the port that USB-SD/MMC controller IC is connected.
With this configuration, all Read/Write/Remove functions correctly worked.
But there is still one issue that task tray in windows shows an error, “Unknown USB device (Port Reset Failure)” like the below figure(Sorry, it’s Japanese).
Then I have two questions.
Regards,
Oba
Hello Oba-san,
Setting a port as removable or non-removable through the registers doesn't change the hub's behavior directly, it will only change what the hub reports to the host in its usb descriptors. This information may impact how the host accesses the hub and its downstream devices. Is the connected downstream device a USB 3.0 or USB 2.0 device? For a quick test, could they check if changing the setting of FULLPWRMGMTz impacts the system behavior?
Regards,
JMMN
Hello JMMN,
The downstream device is USB2.0 device. The customer is on vacation this week. I'll ask to test changing FULLPWRMGMTz next week.
What kind of result could happen by this change?
Regards,
Oba
Hi Oba,
The hub reporting as not having downstream port power switches (FULLPWRMGMTz = 1) changes the "powered off" behavior of the downstream ports for USB 3.0. For USB 2.0, there is no defined state machine difference based on power switches, but the driver behavior may change.
Regards,
JMMN