From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Anholt Subject: Re: [PATCH] spi: bcm2835aux: ensure interrupts are enabled for shared handler Date: Thu, 03 May 2018 14:15:32 -0700 Message-ID: <87efiso2yz.fsf@anholt.net> References: <20180503180945.3502-1-robh@kernel.org> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============5457679589648617855==" Cc: Stefan Wahren , Florian Fainelli , Scott Branden , Marc Zyngier , Ray Jui , Alexander Graf , linux-spi@vger.kernel.org, bcm-kernel-feedback-list@broadcom.com, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org To: Rob Herring , Mark Brown Return-path: In-Reply-To: <20180503180945.3502-1-robh@kernel.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org List-Id: linux-spi.vger.kernel.org --===============5457679589648617855== Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" --=-=-= Content-Type: text/plain Rob Herring writes: > The BCM2835 AUX SPI has a shared interrupt line (with AUX UART). > Downstream fixes this with an AUX irqchip to demux the IRQ sources and a > DT change which breaks compatibility with older kernels. The AUX irqchip > was already rejected for upstream[1] and the DT change would break > working systems if the DTB is updated to a newer one. The latter issue > was brought to my attention by Alex Graf. > > The root cause however is a bug in the shared handler. Shared handlers > must check that interrupts are actually enabled before servicing the > interrupt. Add a check that the TXEMPTY or IDLE interrupts are enabled. It looks to me like we'd only return IRQ_HANDLED if we did work that needed doing. Is this check effectively doing some interlock to make sure that we've already started bcm2835aux_spi_transfer_one_irq() and aren't just racing against transaction setup? --=-=-= Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE/JuuFDWp9/ZkuCBXtdYpNtH8nugFAlrre/QACgkQtdYpNtH8 nuiTFA/+JXtOPIeC3pRE8QTQu2ZkVPSVHWI3uvV5tmdTxXlgxEDCkAozWMM05InI NTGg1wdLrmFkBwj5C1iEa2tnAbGAOi8LnlAfhIBkEE32gR0T3hIOLEguzb3Es1zz LmLOk563jwmX5zCArJ4cu1d7vHMDucfIHFuqlO9d8s32utBRBeMcecpBTKuMEdQp 6v9fZItX2oj5iuI2TRfW5+icBpZ5/67bZ41lk1VSOgIqpkSF/Qsq9SRNOMOHe3R5 DcwETAU8LbNH8XCO+j0PRIC++YLj3fhPJBlwkgQloH0pnLeHzqYqrmx12xuhMnFm WjWwTR657jL1KUnAiVCDNCBvV5PoorxHw+u1tfWPp0HXJaM9vLfCz/cC/pa+PIoL 5cnIiVeIW1Ry3FOnAkMi4lDrIp8+h6AUYnmf3LxW/W3eUniX8sJwDBbbP5ob0351 Ar/Cbu8lu2uT+fts5w3EVW5CJhQE5dPjfXq2d+K0gvZes2bzhRT+ed8J8GhFl7/z 2XaJ5lIAwB+AM8FUz4s6yFw3pV0NSFPn/WtFlnPL0bQKri3z8sAAcrhHM+dCspF2 PScYMsQwhyoSxsMoC2CtQKIvXxRR9RqrrN6rzEGTRSvc5B035nMNQ468EVqos1eW VgC7e7DXwTfljoc0DUCuyUFDUGc9kOC+ji3VAseUQ58P2QFUTcY= =6QOu -----END PGP SIGNATURE----- --=-=-=-- --===============5457679589648617855== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============5457679589648617855==-- From mboxrd@z Thu Jan 1 00:00:00 1970 From: eric@anholt.net (Eric Anholt) Date: Thu, 03 May 2018 14:15:32 -0700 Subject: [PATCH] spi: bcm2835aux: ensure interrupts are enabled for shared handler In-Reply-To: <20180503180945.3502-1-robh@kernel.org> References: <20180503180945.3502-1-robh@kernel.org> Message-ID: <87efiso2yz.fsf@anholt.net> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Rob Herring writes: > The BCM2835 AUX SPI has a shared interrupt line (with AUX UART). > Downstream fixes this with an AUX irqchip to demux the IRQ sources and a > DT change which breaks compatibility with older kernels. The AUX irqchip > was already rejected for upstream[1] and the DT change would break > working systems if the DTB is updated to a newer one. The latter issue > was brought to my attention by Alex Graf. > > The root cause however is a bug in the shared handler. Shared handlers > must check that interrupts are actually enabled before servicing the > interrupt. Add a check that the TXEMPTY or IDLE interrupts are enabled. It looks to me like we'd only return IRQ_HANDLED if we did work that needed doing. Is this check effectively doing some interlock to make sure that we've already started bcm2835aux_spi_transfer_one_irq() and aren't just racing against transaction setup? -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 832 bytes Desc: not available URL: