From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (bilbo.ozlabs.org [203.11.71.1]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 40Ln4Y5C1YzF1Rd for ; Thu, 12 Apr 2018 00:49:33 +1000 (AEST) In-Reply-To: <20180410114933.24581-2-npiggin@gmail.com> To: Nicholas Piggin , linuxppc-dev@lists.ozlabs.org From: Michael Ellerman Cc: Nicholas Piggin Subject: Re: [1/3] powerpc/powernv: define a standard delay for OPAL_BUSY type retry loops Message-Id: <40Ln4Y2zCHz9s4Z@ozlabs.org> Date: Thu, 12 Apr 2018 00:49:33 +1000 (AEST) List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Tue, 2018-04-10 at 11:49:31 UTC, Nicholas Piggin wrote: > This is the start of an effort to tidy up and standardise all the > delays. Existing loops have a range of delay/sleep periods from 1ms > to 20ms, and some have no delay. They all loop forever except rtc, > which times out after 10 retries, and that uses 10ms delays. So use > 10ms as our standard delay. The OPAL maintainer agrees 10ms is a > reasonable starting point. > > The idea is to use the same recipe everywhere, once this is proven to > work then it will be documented as an OPAL API standard. Then both > firmware and OS can agree, and if a particular call needs something > else, then that can be documented with reasoning. > > This is not the end-all of this effort, it's just a relatively easy > change that fixes some existing high latency delays. There should be > provision for standardising timeouts and/or interruptible loops where > possible, so non-fatal firmware errors don't cause hangs. > > Signed-off-by: Nicholas Piggin Applied to powerpc fixes, thanks. https://git.kernel.org/powerpc/c/34dd25de9fe3f60bfdb31b473bf04b cheers