From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Mon, 9 Apr 2018 16:13:42 +1000 From: Nicholas Piggin To: Benjamin Herrenschmidt Cc: linuxppc-dev@lists.ozlabs.org, skiboot@lists.ozlabs.org Subject: Re: [PATCH v2 4/9] powerpc/powernv: OPAL console standardise OPAL_BUSY loops Message-ID: <20180409161342.02f41b8a@roar.ozlabs.ibm.com> In-Reply-To: <1523253213.11062.7.camel@kernel.crashing.org> References: <20180409052431.26405-1-npiggin@gmail.com> <20180409052431.26405-5-npiggin@gmail.com> <1523253213.11062.7.camel@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 09 Apr 2018 15:53:33 +1000 Benjamin Herrenschmidt wrote: > On Mon, 2018-04-09 at 15:24 +1000, Nicholas Piggin wrote: > > Convert to using the standard delay poll/delay form. > > > > The console code: > > > > - Did not previously delay or sleep in its busy loop. > > > > Cc: Benjamin Herrenschmidt > > Signed-off-by: Nicholas Piggin > > Does it help with anything ? We don't technically *have* to delay or > wait, I thought it would be good to try to hit the console as fast as > possible in that case... We can always make exceptions to the standard form, but in those cases I would like to document it in the OPAL API and comment for the Linux side. My thinking in this case is that it reduces time in firmware and in particular holding console locks. Is it likely / possible that we don't have enough buffering or some other issue makes it worth retrying so quickly? Thanks, Nick