[PATCH v6 6/7] gpio: aspeed: Add the flush write to ensure the write complete.
Andrew Jeffery
andrew at codeconstruct.com.au
Mon Sep 30 14:38:18 AEST 2024
On Fri, 2024-09-27 at 19:17 +0800, Billy Tsai 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 at aspeedtech.com>
Reviewed-by: Andrew Jeffery <andrew at codeconstruct.com.au>
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