From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gloria.sntech.de (gloria.sntech.de [185.11.138.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 06B302F28 for ; Thu, 25 Aug 2022 12:05:32 +0000 (UTC) Received: from ip5b412258.dynamic.kabel-deutschland.de ([91.65.34.88] helo=diego.localnet) by gloria.sntech.de with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1oRBbh-0001K3-BL; Thu, 25 Aug 2022 14:05:09 +0200 From: Heiko =?ISO-8859-1?Q?St=FCbner?= To: Srinivas Kandagatla , Chen-Yu Tsai , Jernej Skrabec , linux-arm-kernel@lists.infradead.org Cc: Samuel Holland , Greg Kroah-Hartman , Krzysztof Kozlowski , Rob Herring , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev, Samuel Holland Subject: Re: [PATCH 1/4] nvmem: sunxi_sid: Always use 32-bit MMIO reads Date: Thu, 25 Aug 2022 14:05:08 +0200 Message-ID: <5410996.rnE6jSC6OK@diego> In-Reply-To: <20220814173656.11856-2-samuel@sholland.org> References: <20220814173656.11856-1-samuel@sholland.org> <20220814173656.11856-2-samuel@sholland.org> Precedence: bulk X-Mailing-List: linux-sunxi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Am Sonntag, 14. August 2022, 19:36:52 CEST schrieb Samuel Holland: > The SID SRAM on at least some SoCs (A64 and D1) returns different values > when read with bus cycles narrower than 32 bits. This is not immediately > obvious, because memcpy_fromio() uses word-size accesses as long as > enough data is being copied. > > The vendor driver always uses 32-bit MMIO reads, so do the same here. > This is faster than the register-based method, which is currently used > as a workaround on A64. And it fixes the values returned on D1, where > the SRAM method was being used. > > The special case for the last word is needed to maintain .word_size == 1 > for sysfs ABI compatibility, as noted previously in commit de2a3eaea552 > ("nvmem: sunxi_sid: Optimize register read-out method"). > > Fixes: 07ae4fde9efa ("nvmem: sunxi_sid: Add support for D1 variant") > Signed-off-by: Samuel Holland On a D1-Nezha: Tested-by: Heiko Stuebner