linux-kernel - [PATCH v1] iopoll: Tweak readx_poll

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Message-ID: <c2e6af51-5676-3715-6666-c3f18df7b992@free.fr>
Date:   Thu, 13 Jun 2019 14:16:42 +0200
From:   Marc Gonzalez <marc.w.gonzalez@...e.fr>
To:     Matt Wagantall <mattw@...eaurora.org>,
        Mitchel Humpherys <mitchelh@...eaurora.org>,
        Will Deacon <will.deacon@....com>,
        Arnd Bergmann <arnd@...db.de>
Cc:     Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Douglas Anderson <dianders@...omium.org>
Subject: [PATCH v1] iopoll: Tweak readx_poll_timeout sleep range

Chopping max delay in 4 seems excessive. Let's just cut it in half.

Signed-off-by: Marc Gonzalez <marc.w.gonzalez@...e.fr>
---
When max_us=100, old_min was 26 us; new_min would be 50 us
Was there a good reason for the 1/4th?
Is new_min=0 a problem? (for max=1)
---
 include/linux/iopoll.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h
index 3908353deec6..24a00d923c15 100644
--- a/include/linux/iopoll.h
+++ b/include/linux/iopoll.h
@@ -47,7 +47,7 @@
 			break; \
 		} \
 		if (__sleep_us) \
-			usleep_range((__sleep_us >> 2) + 1, __sleep_us); \
+			usleep_range(__sleep_us / 2, __sleep_us); \
 	} \
 	(cond) ? 0 : -ETIMEDOUT; \
 })
-- 
2.17.1