Hi,

On Mon, Mar 9, 2020 at 2:11 PM Stephen Boyd sboyd@kernel.org wrote:

Quoting Mike Tipton (2020-02-14 18:12:32)

...

The current implementation always uses rpmh_write_async, which doesn't wait for completion. That's fine for disable requests since there's no immediate need for the clocks and they can be disabled in the background. However, for enable requests we need to ensure the clocks are actually enabled before returning to the client. Otherwise, clients can end up accessing their HW before the necessary clocks are enabled, which can lead to bus errors.

Use the synchronous version of this API (rpmh_write) for enable requests in the active set to ensure completion.

Completion isn't required for sleep/wake sets, since they don't take effect until after we enter sleep. All rpmh requests are automatically flushed prior to entering sleep.

Fixes: 9c7e47025a6b ("clk: qcom: clk-rpmh: Add QCOM RPMh clock driver") Signed-off-by: Mike Tipton mdtipton@codeaurora.org

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Applied to clk-next but I squashed in some changes to make it easier for me to read.

This landed upstream as commit dad4e7fda4bd ("clk: qcom: clk-rpmh: Wait for completion when enabling clocks") but seemed to have missed stable. Can stable pick it up? It has a Fixes tag so presumably it should be easy to track down where it needs to go.

Thanks!

-Doug