Re: [PATCH v4 6/6] gpio: aspeed: Add the flush write to ensure the write complete.

[Linus Walleij]

On Thu, Sep 19, 2024 at 11:43 AM Billy Tsai <billy_tsai@xxxxxxxxxxxxxx> wrote:

> Performing a dummy read ensures that the register write operation is fully
> completed, mitigating any potential bus delays that could otherwise impact
> the frequency of bitbang usage. E.g., if the JTAG application uses GPIO to
> control the JTAG pins (TCK, TMS, TDI, TDO, and TRST), and the application
> sets the TCK clock to 1 MHz, the GPIO’s high/low transitions will rely on
> a delay function to ensure the clock frequency does not exceed 1 MHz.
> However, this can lead to rapid toggling of the GPIO because the write
> operation is POSTed and does not wait for a bus acknowledgment.
>
> Signed-off-by: Billy Tsai <billy_tsai@xxxxxxxxxxxxxx>

If this applies cleanly on mainline I think it should go into fixes as-is.

Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>

Yours,
Linus Walleij