From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay7-d.mail.gandi.net (relay7-d.mail.gandi.net [217.70.183.200]) (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 B7E047D3E8; Tue, 9 Apr 2024 10:09:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.183.200 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712657369; cv=none; b=Qtodnkk9CX/szB7J0QN9ltmcdPMd++yCWKKnnLrGDAHf2FyoABb/GRrm4+DIO/0QeDoV+OBt4BBdhlzCxuhbXj/mne3ShTNnFng49G0orwB8Ud5YYDgpzp8Ruf4idlr0/6to5M4yN5TnEzePZgsDdAchNQvIkGRLF8kSzPKUwpo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712657369; c=relaxed/simple; bh=kPve59cg+kbjwFG+j4J1S4mcG9qBitt5lHcER6L38Vg=; h=Mime-Version:Content-Type:Date:Message-Id:Cc:To:From:Subject: References:In-Reply-To; b=jw5VwuFeVlqOkW38J/U3vbtW/P59RuDgU2yPtBkpQ8qCbM/0qc2YwbOn+oVJpi8sGFznDzIO3EX2gDqv9su14QIFS3T7EpslS/n5fBOsd+VZCV44KFK4BGkCLcpN5cc9RfMsXFno3UopI/iuCGJrwn1Siw/HQ4nfl4KpoNLtVLU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=ZzEaGpmR; arc=none smtp.client-ip=217.70.183.200 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="ZzEaGpmR" Received: by mail.gandi.net (Postfix) with ESMTPSA id E25E620005; Tue, 9 Apr 2024 10:09:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1712657358; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qkOZRgZN7hbEc/8b8ArAg5uS4IlZ6EWpP5ZMcV/G7KA=; b=ZzEaGpmR+ztCVSdv0AhiewnxS8iPe15xzID6gNN68isgCoSYX+e9U+VXNluv2vXqlS3veH X/51oO3V9KHqMpO5EylWZ5BKbj7b+xNtq0IluWlOJjKfMOVKC8Bevot0b1xytcbAbNwTEl HIa8GAj54hZ258Q3QsYdUoH4HU/sxg6r+dmlH5TLlEHXMRwVkirZQAvFMwcwlGy6T/1aQa aJl9JfG58zDl+nB87GB9xMxXlvnyTFtPfRk/lYDmtD+1qPXOapm4ZEna/h32JizoB4Pd/Z FnkzI5Lm/VRCexTT2TMXmKtPjH3sLToc/qUz90Rud8UdLKafS5IuRHz5jp2fnw== Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Tue, 09 Apr 2024 12:09:17 +0200 Message-Id: Cc: "Rob Herring" , "Krzysztof Kozlowski" , "Conor Dooley" , "Vaishnav Achath" , "Thomas Bogendoerfer" , "Rob Herring" , , , , , "Vladimir Kondratiev" , "Gregory CLEMENT" , "Thomas Petazzoni" , "Tawfik Bayouk" To: "Mark Brown" From: =?utf-8?q?Th=C3=A9o_Lebrun?= Subject: Re: [PATCH v2 08/11] spi: cadence-qspi: add early busywait to cqspi_wait_for_bit() X-Mailer: aerc 0.15.2 References: <20240405-cdns-qspi-mbly-v2-0-956679866d6d@bootlin.com> <20240405-cdns-qspi-mbly-v2-8-956679866d6d@bootlin.com> <1f7087ad-824e-47fe-9953-ed5152c8f18f@sirena.org.uk> <9cb48440-c71e-4a73-8104-4780f0e98e72@sirena.org.uk> In-Reply-To: <9cb48440-c71e-4a73-8104-4780f0e98e72@sirena.org.uk> X-GND-Sasl: theo.lebrun@bootlin.com Hello, On Mon Apr 8, 2024 at 6:40 PM CEST, Mark Brown wrote: > On Mon, Apr 08, 2024 at 04:42:43PM +0200, Th=C3=A9o Lebrun wrote: > > On Mon Apr 8, 2024 at 4:16 PM CEST, Mark Brown wrote: > > > On Fri, Apr 05, 2024 at 05:02:18PM +0200, Th=C3=A9o Lebrun wrote: > > > > > The reason is to avoid hrtimer interrupts on the system. All read > > > > operations take less than 100=C2=B5s. > > > > Why would this be platform specific, this seems like a very standard > > > optimisation technique? > > > It does not make sense if you know that all read operations take more > > than 100=C2=B5s. I preferred being conservative. If you confirm it make= s > > sense I'll remove the quirk. > > It does seem plausible at least, and the time could be made a tuneable > with quirks or otherwise if that's needed. I think I'd expect the MIPS > platform you're working with to be towards the lower end of performance > for systems that are new enough to have this hardware. Next revision will do the same busywait behavior unconditionally then. Thanks! -- Th=C3=A9o Lebrun, Bootlin Embedded Linux and Kernel engineering https://bootlin.com