From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 B1F67443A97; Tue, 1 Sep 2026 19:47:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788292058; cv=none; b=QOOG+Wt8v/u0HVB+OQF8NZ03O2rRF7G7WLr7ved5VCsasXpRypd/oVbuS1pek6N3WCBtomT7fBrL4M1+k8NcxKA72iLEiibTWeWue3LcJaSwyONvfP4zXgWul50cfEf/Z/xXvXG45hJpbB0zpRtNi9fGtFs34mHKR8LXKUIy/1E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788292058; c=relaxed/simple; bh=S6Ze5dH30c1sk13lINsxsruT9DPKAtqX7682wKNvFoM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ZY76xw/baSTX3dPcyhSibNs4OoTR1G8Xn1rt6ZkiawOajpbk7ntjHcWB2eQRrtDaGuX2ICPECuZwCg67FI3wW/6qP/zzxJ5JNyvYMji+ei4ToKjZRkfnLoEfRHjhSU+2l1NcDk3mLGW1uhY4uxFvcM65gBgeuKKq18l8dMToNTQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=KGQ6Sv5V; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=iMGMW1+A; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="KGQ6Sv5V"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="iMGMW1+A" Date: Tue, 1 Sep 2026 21:47:29 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1788292050; 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: in-reply-to:in-reply-to:references:references; bh=8kVakSZKJ+/biQmo1FhyfgpI2TOx3aJuye+azQYfGnU=; b=KGQ6Sv5V/WARQz5NH6d3Sb3JusTpH/c7YNqpIgnd9h+VIJikdiibfvsSkNPtm2bSP/sNrE AvHRhw0oEpHKfBQZW28q8HHevQzjUQdV4cj7aH7bgegDqLPaMvv5rlmLb9YdaAASayjDzJ xVlgYYJBlHfQhauHSraIKwBiw3GZR6FVxUYNYgUeeeBA0exkdQe8TVBBAh0RBWdGZWXBvF h3NuDkP6SH5UBdfiI5GtXrMum8aDWrwZ4iiAoPmhDv2/N8lPNbi1ApDs+lQBJonjZYRdM7 zXdBN2cuHfTH8WIKTdW+KcAncRBjoEAr8ptEteLUVDWDo0bwvmdcdOyjZCGUcA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1788292050; 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: in-reply-to:in-reply-to:references:references; bh=8kVakSZKJ+/biQmo1FhyfgpI2TOx3aJuye+azQYfGnU=; b=iMGMW1+AP/4HcbKeF6pbp3Co1it0nekDJR7mljsr5oAtbOpE4Avv74bSlvj0UHwdzmMNy2 /d0cJ8VUYMLn94Bw== From: Sebastian Andrzej Siewior To: Marek Vasut Cc: netdev@vger.kernel.org, "David S. Miller" , Andrew Lunn , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Yicong Hui , kernel@dh-electronics.com, linux-kernel@vger.kernel.org Subject: Re: [net,PATCH v1] net: ks8851: Fix receiver error in 100BASE-TX mode following software power-down Message-ID: <20260901194729.r9N1Z-4-@linutronix.de> References: <20260901173925.96183-1-marex@nabladev.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260901173925.96183-1-marex@nabladev.com> On 2026-09-01 19:39:14 [+0200], Marek Vasut wrote: > KSZ8851 errata sheet DS80000716D-page 4 Module 3 [1] states that, > when issuing a software power-down (PMECR[1:0] = 10) followed by a > power-on (PMECR[1:0] = 00), the receiver circuit can fail to start > properly preventing communication. The Transmitter will still send > data, but no data will be received. > > The errata sheet also includes a workaround, which states that, > it is recommended that the software power-down feature not be used. > > Implement that workaround and drop the entry into software power-down > mode. The ks8851_write_mac_addr() calls entry into normal power-on > mode at the very beginning of the function, therefore dropping the > second call to enter software power-down mode is sufficient here. > The ks8851_net_stop() can only be called after ks8851_net_start() > was already called, and ks8851_net_start() also makes the MAC enter > normal power-on mode, therefore it is also fine to drop the call to > enter software power-down mode from ks8851_net_stop(). > > This will lead to slight increase in power consumption, but it also > fixes a sporadic problem which occurs at least on KSZ8851-16MLL, on > which this fix is tested. > > [1] https://ww1.microchip.com/downloads/en/DeviceDoc/80000716D.pdf > > Fixes: 3ba81f3ece3c ("net: Micrel KS8851 SPI network driver") > Signed-off-by: Marek Vasut Reviewed-by: Sebastian Andrzej Siewior The patch description matches the errata document and the change. Sebastian