From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2F80F13A3E8; Wed, 21 Aug 2024 21:43:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724276595; cv=none; b=lUKPW5yYsd7xGD5U/g+j6ZQ5jdpeJQ3c7ZGB6AOXl/6nt63mQ1fVRepcZgnsMnfjMeA2BN/TX67i5K1VFYkNhk2ndVPg10CyV/2koO8XwfXB6quF0nvA01DeWovrlx+OdL5edD0LadkYKaUbSU8V9jeDevIXwah2emqGYa6h0Ng= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724276595; c=relaxed/simple; bh=0Yu32Y2Y97+J7V2U2AZCL0+qw3bl5E2OZ9XQy9g/wxI=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=sSAKvsdY9OclugnwZkyDsrV6a+pz+59AWAPKsYXeT7zEqY+yPwfYvEe0CaIUmN6hxv2IxUTGqOOo3VxV1MsQSf0/y5uHz0gtph+4MxjmjwVRiSpDQ8LlrapCy2dyMDog9fPV5H9mXvjv6LCjppvm1guyB6TizODK0hZOizYN2Fg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=OhjPjrLs; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OhjPjrLs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 66549C32781; Wed, 21 Aug 2024 21:43:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724276594; bh=0Yu32Y2Y97+J7V2U2AZCL0+qw3bl5E2OZ9XQy9g/wxI=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=OhjPjrLsmnbkOEwzQ9TSQaOGfhTR81foJZIrjn0jymdJ+DsxoJcgziNLu+BGWtDNN s8/2P9SG/UL0N0I4n/zenqFhKZy+RdEm288mPAHUHy7z+BJmrk+loKShjm/EU/3GcL iYjRgE/CEVnsy8cNEaMZBfT6eYkgsD3bydNA8R+jwhITiKi8KaMj1GVTjGHWhVWV11 KzqtRREbV7A9NVOQ5sABE8OGsfW9ad8dJ2WxZqFWh2NSNeeLgFAGExDKKf6NQYiYXF slZHRazBltWpNdsA+eCG6oi1lYoowuOqOMyo39nRRvGrW9I+AWhRYBk5nJC1jkWAXn 5YlrqUOysjyNA== Date: Wed, 21 Aug 2024 16:43:12 -0500 From: Bjorn Helgaas To: Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= Cc: Manivannan Sadhasivam , lpieralisi@kernel.org, robh@kernel.org, bhelgaas@google.com, linux-arm-msm@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] PCI: qcom-ep: Move controller cleanups to qcom_pcie_perst_deassert() Message-ID: <20240821214312.GA270533@bhelgaas> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20240813202837.GE1922056@rocinante> On Wed, Aug 14, 2024 at 05:28:37AM +0900, Krzysztof Wilczyński wrote: > > Currently, the endpoint cleanup function dw_pcie_ep_cleanup() and EPF > > deinit notify function pci_epc_deinit_notify() are called during the > > execution of qcom_pcie_perst_assert() i.e., when the host has asserted > > PERST#. But quickly after this step, refclk will also be disabled by the > > host. > > > > All of the Qcom endpoint SoCs supported as of now depend on the refclk from > > the host for keeping the controller operational. Due to this limitation, > > any access to the hardware registers in the absence of refclk will result > > in a whole endpoint crash. Unfortunately, most of the controller cleanups > > require accessing the hardware registers (like eDMA cleanup performed in > > dw_pcie_ep_cleanup(), powering down MHI EPF etc...). So these cleanup > > functions are currently causing the crash in the endpoint SoC once host > > asserts PERST#. > > > > One way to address this issue is by generating the refclk in the endpoint > > itself and not depending on the host. But that is not always possible as > > some of the endpoint designs do require the endpoint to consume refclk from > > the host (as I was told by the Qcom engineers). > > > > So let's fix this crash by moving the controller cleanups to the start of > > the qcom_pcie_perst_deassert() function. qcom_pcie_perst_deassert() is > > called whenever the host has deasserted PERST# and it is guaranteed that > > the refclk would be active at this point. So at the start of this function, > > the controller cleanup can be performed. Once finished, rest of the code > > execution for PERST# deassert can continue as usual. > > Applied to controller/qcom, thank you! > > [1/1] PCI: qcom-ep: Move controller cleanups to qcom_pcie_perst_deassert() > https://git.kernel.org/pci/pci/c/6960cdc1ef97 I dropped this for now, looking for a new simpler version without "cleanup_pending" and a similar change for tegra194 (separate patch). I think it's still an open question whether both pci_epc_deinit_notify() and pci_epc_init_notify() are needed, but that should be separate and I don't think that would fix a crash. You said this was not strictly v6.11 material, but it does fix a crash, and it only touches the endpoint driver, so ... it seems like a possible candidate, especially if we can identify a recent commit that caused the crash. Bjorn