[U-Boot] [PATCH v6 01/15] Add an I/O tracing feature

[Simon Glass]

On 11 June 2014 23:29, Simon Glass <sjg at chromium.org> wrote:
> When debugging drivers it is useful to see what I/O accesses were done
> and in what order.
>
> Even if the individual accesses are of little interest it can be useful to
> verify that the access pattern is consistent each time an operation is
> performed. In this case a checksum can be used to characterise the operation
> of a driver. The checksum can be compared across different runs of the
> operation to verify that the driver is working properly.
>
> In particular, when performing major refactoring of the driver, where the
> access pattern should not change, the checksum provides assurance that the
> refactoring work has not broken the driver.
>
> Add an I/O tracing feature and associated commands to provide this facility.
> It works by sneaking into the io.h heder for an architecture and redirecting
> I/O accesses through its tracing mechanism.
>
> For now no commands are provided to examine the trace buffer. The format is
> fairly simple, so 'md' is a reasonable substitute.
>
> Note: The checksum feature is only useful for I/O regions where the contents
> do not change outside of software control. Where this is not suitable you can
> fall back to manually comparing the addresses. It might be useful to enhance
> tracing to only checksum the accesses and not the data read/written.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>

Applied to u-boot-dm/master.