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Fri, 01 Aug 2025 02:03:16 -0700 (PDT) Date: Fri, 1 Aug 2025 09:03:15 +0000 In-Reply-To: <20250627123854.921704-1-jfalempe@redhat.com> Mime-Version: 1.0 References: <20250627123854.921704-1-jfalempe@redhat.com> Message-ID: Subject: Re: [PATCH v2] drm/panic: Add a u64 divide by 10 for arm32 From: Alice Ryhl To: Jocelyn Falempe Cc: Andrei Lalaev , Miguel Ojeda , Christian Schrefl , Arnd Bergmann , Russell King , Paolo Bonzini , rust-for-linux , Linux ARM , Thomas Zimmermann , Javier Martinez Canillas , Maarten Lankhorst , Maxime Ripard , David Airlie , Simona Vetter , dri-devel@lists.freedesktop.org Content-Type: text/plain; charset="utf-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250801_020318_676092_B18E01BB X-CRM114-Status: GOOD ( 11.37 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jun 27, 2025 at 02:38:19PM +0200, Jocelyn Falempe wrote: > On 32bits ARM, u64 divided by a constant is not optimized to a > multiply by inverse by the compiler [1]. > So do the multiply by inverse explicitly for this architecture. > > Link: https://github.com/llvm/llvm-project/issues/37280 [1] > Reported-by: Andrei Lalaev > Closes: https://lore.kernel.org/dri-devel/c0a2771c-f3f5-4d4c-aa82-d673b3c5cb46@gmail.com/ > Fixes: 675008f196ca ("drm/panic: Use a decimal fifo to avoid u64 by u64 divide") > Signed-off-by: Jocelyn Falempe Reviewed-by: Alice Ryhl