Messages in this thread | | | From | Dylan Hung <> | Subject | RE: [PATCH v2 3/3] ARM: dts: aspeed: add reset properties into MDIO nodes | Date | Tue, 22 Mar 2022 03:22:37 +0000 |
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> -----Original Message----- > From: Andrew Lunn [mailto:andrew@lunn.ch] > Sent: 2022年3月22日 11:01 AM > To: Dylan Hung <dylan_hung@aspeedtech.com> > Cc: Krzysztof Kozlowski <krzk@kernel.org>; robh+dt@kernel.org; > joel@jms.id.au; andrew@aj.id.au; hkallweit1@gmail.com; > linux@armlinux.org.uk; davem@davemloft.net; kuba@kernel.org; > pabeni@redhat.com; p.zabel@pengutronix.de; devicetree@vger.kernel.org; > linux-arm-kernel@lists.infradead.org; linux-aspeed@lists.ozlabs.org; > linux-kernel@vger.kernel.org; netdev@vger.kernel.org; BMC-SW > <BMC-SW@aspeedtech.com>; stable@vger.kernel.org > Subject: Re: [PATCH v2 3/3] ARM: dts: aspeed: add reset properties into MDIO > nodes > > On Tue, Mar 22, 2022 at 02:32:13AM +0000, Dylan Hung wrote: > > > -----Original Message----- > > > From: Krzysztof Kozlowski [mailto:krzk@kernel.org] > > > Sent: 2022年3月21日 11:53 PM > > > To: Dylan Hung <dylan_hung@aspeedtech.com>; robh+dt@kernel.org; > > > joel@jms.id.au; andrew@aj.id.au; andrew@lunn.ch; > > > hkallweit1@gmail.com; linux@armlinux.org.uk; davem@davemloft.net; > > > kuba@kernel.org; pabeni@redhat.com; p.zabel@pengutronix.de; > > > devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org; > > > linux-aspeed@lists.ozlabs.org; linux-kernel@vger.kernel.org; > > > netdev@vger.kernel.org > > > Cc: BMC-SW <BMC-SW@aspeedtech.com>; stable@vger.kernel.org > > > Subject: Re: [PATCH v2 3/3] ARM: dts: aspeed: add reset properties > > > into MDIO nodes > > > > > > On 21/03/2022 10:56, Dylan Hung wrote: > > > > Add reset control properties into MDIO nodes. The 4 MDIO > > > > controllers in > > > > AST2600 SOC share one reset control bit SCU50[3]. > > > > > > > > Signed-off-by: Dylan Hung <dylan_hung@aspeedtech.com> > > > > Cc: stable@vger.kernel.org > > > > > > Please describe the bug being fixed. See stable-kernel-rules. > > > > Thank you for your comment. > > The reset deassertion of the MDIO device was usually done by the > bootloader (u-boot). > > However, one of our clients uses proprietary bootloader and doesn't > > deassert the MDIO reset so failed to access the HW in kernel driver. > > So are you saying mainline u-boot releases the reset? > Yes, if the mdio devices are used in u-boot.
> > The reset deassertion is missing in the kernel driver since it was > > created, should I add a BugFix for the first commit of this driver? > > Yes, that is normal. Ideally the kernel should not depend on u-boot, because > often people want to use other bootloaders, e.g. barebox. You should also > consider kexec, where one kernel hands over to another kernel, without the > bootloader being involved. In such a situation, you ideally want to assert and > deassert the reset just to clean away any state the old kernel left around. > > But please do note, that the reset is optional, since you need to be able to > work with old DT blobs which don't have the reset property in them. >
Thank you. I will let the reset property be optional and modify the error-checking in the driver accordingly in V3.
> Andrew > >
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