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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 626CBC433F5 for ; Sat, 23 Apr 2022 13:15:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232643AbiDWNR4 (ORCPT ); Sat, 23 Apr 2022 09:17:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58604 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235666AbiDWNRg (ORCPT ); Sat, 23 Apr 2022 09:17:36 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 955E81DD225; Sat, 23 Apr 2022 06:14:39 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 15A4CB801BD; Sat, 23 Apr 2022 13:14:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 87D7CC385A5; Sat, 23 Apr 2022 13:14:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1650719676; bh=EhGNChbTex4daXC/4M0L+MFTZGt5iVXyh5mOH6CzWeM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=WEmbry3swwcKTDm+Y+ygHIERtUNF07Xpg8tZ0fNPrw3SURPGXJCuDUSlWatSz4NzS J7WRYJHTHP1LG048fDCbUzh0D8pR1so2Tb81e1ggWtWQW5vKmUM8ts5CYeTJmRmcue nEQQZR189UIYCpuyXDhZjJ03PaRJJg1kUJEMY/QDNjpxl3ij7XOCjeJ71k+HsgWREE rFVNuLh8oQ8v9npLTz7zopnpRp/wOnZL+8kp6tZcF6/g5ut7lNG7dASJC0YpwHVE7X R4FX+Izd/8WE7NmavgLgGwHE0LDpZO0bIbmbQN2OkA4PnLPWQS04z2sAF1Vq0IIe6d /RnyZwKr6/Z+w== Date: Sat, 23 Apr 2022 18:44:29 +0530 From: Manivannan Sadhasivam To: Jeffrey Hugo Cc: quic_hemantk@quicinc.com, quic_bbhatt@quicinc.com, mhi@lists.linux.dev, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4] bus: mhi: host: Wait for ready state after reset Message-ID: <20220423131429.GN374560@thinkpad> References: <1650302562-30964-1-git-send-email-quic_jhugo@quicinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1650302562-30964-1-git-send-email-quic_jhugo@quicinc.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Apr 18, 2022 at 11:22:42AM -0600, Jeffrey Hugo wrote: > After the device has signaled the end of reset by clearing the reset bit, > it will automatically reinit MHI and the internal device structures. Once > That is done, the device will signal it has entered the ready state. > > Signaling the ready state involves sending an interrupt (MSI) to the host > which might cause IOMMU faults if it occurs at the wrong time. > > If the controller is being powered down, and possibly removed, then the > reset flow would only wait for the end of reset. At which point, the host > and device would start a race. The host may complete its reset work, and > remove the interrupt handler, which would cause the interrupt to be > disabled in the IOMMU. If that occurs before the device signals the ready > state, then the IOMMU will fault since it blocked an interrupt. While > harmless, the fault would appear like a serious issue has occurred so let's > silence it by making sure the device hits the ready state before the host > completes its reset processing. > > Signed-off-by: Jeffrey Hugo > Reviewed-by: Hemant Kumar > Reviewed-by: Manivannan Sadhasivam Applied to mhi-next! Thanks, Mani > --- > > v4: > Cleanup email domain change > > v3: > Rebase and use dev_err over dev_warn > > v2: > Fix subject and remove use of cur_state > > drivers/bus/mhi/host/pm.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/bus/mhi/host/pm.c b/drivers/bus/mhi/host/pm.c > index 3d90b8e..c000a92 100644 > --- a/drivers/bus/mhi/host/pm.c > +++ b/drivers/bus/mhi/host/pm.c > @@ -476,6 +476,15 @@ static void mhi_pm_disable_transition(struct mhi_controller *mhi_cntrl) > * hence re-program it > */ > mhi_write_reg(mhi_cntrl, mhi_cntrl->bhi, BHI_INTVEC, 0); > + > + if (!MHI_IN_PBL(mhi_get_exec_env(mhi_cntrl))) { > + /* wait for ready to be set */ > + ret = mhi_poll_reg_field(mhi_cntrl, mhi_cntrl->regs, > + MHISTATUS, > + MHISTATUS_READY_MASK, 1, 25000); > + if (ret) > + dev_err(dev, "Device failed to enter READY state\n"); > + } > } > > dev_dbg(dev, > -- > 2.7.4 >