From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 00B44C83007 for ; Wed, 29 Apr 2020 07:54:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D208B2083B for ; Wed, 29 Apr 2020 07:54:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726486AbgD2HyC (ORCPT ); Wed, 29 Apr 2020 03:54:02 -0400 Received: from sauhun.de ([88.99.104.3]:53636 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726175AbgD2HyB (ORCPT ); Wed, 29 Apr 2020 03:54:01 -0400 Received: from localhost (p54B330EB.dip0.t-ipconnect.de [84.179.48.235]) by pokefinder.org (Postfix) with ESMTPSA id 3F6972C08B2; Wed, 29 Apr 2020 09:53:59 +0200 (CEST) Date: Wed, 29 Apr 2020 09:53:57 +0200 From: Wolfram Sang To: ryan_chen Cc: Brendan Higgins , Benjamin Herrenschmidt , Joel Stanley , Andrew Jeffery , linux-i2c@vger.kernel.org, openbmc@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v0 linux master] i2c/busses: Avoid i2c interrupt status clear race condition. Message-ID: <20200429075357.GA1957@kunai> References: <20200429033737.2781-1-ryan_chen@aspeedtech.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="0F1p//8PRICkK4MW" Content-Disposition: inline In-Reply-To: <20200429033737.2781-1-ryan_chen@aspeedtech.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --0F1p//8PRICkK4MW Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Apr 29, 2020 at 11:37:37AM +0800, ryan_chen wrote: > In AST2600 there have a slow peripheral bus between CPU > and i2c controller. > Therefore GIC i2c interrupt status clear have delay timing, > when CPU issue write clear i2c controller interrupt status. > To avoid this issue, the driver need have read after write > clear at i2c ISR. >=20 > Signed-off-by: ryan_chen v0? is it a prototype? And is there maybe a Fixes: tag for it? > --- > drivers/i2c/busses/i2c-aspeed.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) >=20 > diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-asp= eed.c > index 07c1993274c5..f51702d86a90 100644 > --- a/drivers/i2c/busses/i2c-aspeed.c > +++ b/drivers/i2c/busses/i2c-aspeed.c > @@ -603,6 +603,7 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void *= dev_id) > /* Ack all interrupts except for Rx done */ > writel(irq_received & ~ASPEED_I2CD_INTR_RX_DONE, > bus->base + ASPEED_I2C_INTR_STS_REG); > + readl(bus->base + ASPEED_I2C_INTR_STS_REG); > irq_remaining =3D irq_received; > =20 > #if IS_ENABLED(CONFIG_I2C_SLAVE) > @@ -645,9 +646,11 @@ static irqreturn_t aspeed_i2c_bus_irq(int irq, void = *dev_id) > irq_received, irq_handled); > =20 > /* Ack Rx done */ > - if (irq_received & ASPEED_I2CD_INTR_RX_DONE) > + if (irq_received & ASPEED_I2CD_INTR_RX_DONE) { > writel(ASPEED_I2CD_INTR_RX_DONE, > bus->base + ASPEED_I2C_INTR_STS_REG); > + readl(bus->base + ASPEED_I2C_INTR_STS_REG); > + } > spin_unlock(&bus->lock); > return irq_remaining ? IRQ_NONE : IRQ_HANDLED; > } > --=20 > 2.17.1 >=20 --0F1p//8PRICkK4MW Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEOZGx6rniZ1Gk92RdFA3kzBSgKbYFAl6pMo4ACgkQFA3kzBSg KbbntRAAs++ZnC+iCmSLY5Q3M4OON+jEs3K4ZhdSuNgzbZsLaWVt5Cx7cCjT/JDi 988C8kzysPKL8Cknlqyv4GBus0cCPwylvFZGHWXdot89RmG4stjYb3JbaV+Qm9Ov 8bCKE8xEWEHyYFFEgreqtLbEFCnHCNf7TnX21b8+L6E988R1AE7r5qIFCTuK1/4/ hrNCRmEoXYLp0pSDC6BuAgJvayrewlTkvCfnBVv39FzN95ghtC21cC73I6SKfDat qxCyKy1x++V6n03sprTFgc8MCqOpYu6rIgFKm94NSltyJWaRAZKY1vd/Pzj7D0Oc UPhtu7ldQAbllMAZmMutCDf8m0ek+Ob4jHF+DQKqq2E8MQZs35RxrNnDYzFOLm7r NISJkGAZ6ZmC3lmyH1t1GRxZls5RfqpUJuVFIke07C4eSO7r6y9rWoOOhzMYJERC cQuG05T6fcJRGx35/h9GHbcb9+kafQXXRaM65H4aEPKBjbtDbyC8j9PT5WGTRFwS kS0iSZ5XnSiCccMv33mJqgotV9yPTaVHstupHCnI7K77MH0b7l4Ni1Q7DAnR0cE/ 7mhN81qc04aqCi4+Zi1PtWRKMBcgvdX9QmHQnt2KYc7kSmgD9gy454O1NOIbA97S c1UOGjbptbrnl1VaH9/o0SldOXlHGdNzkzspFGAhk/5ioC8I2oE= =hr47 -----END PGP SIGNATURE----- --0F1p//8PRICkK4MW--