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Fri, 27 Nov 2020 17:40:44 GMT Sender: jhugo=codeaurora.org@mg.codeaurora.org Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 852F6C43462; Fri, 27 Nov 2020 17:40:43 +0000 (UTC) Received: from [10.226.59.216] (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: jhugo) by smtp.codeaurora.org (Postfix) with ESMTPSA id 5826CC433ED; Fri, 27 Nov 2020 17:40:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 5826CC433ED Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=fail smtp.mailfrom=jhugo@codeaurora.org Subject: Re: [PATCH v3 3/9] mhi: pci-generic: Perform hard reset on remove From: Jeffrey Hugo To: Loic Poulain , manivannan.sadhasivam@linaro.org, hemantk@codeaurora.org Cc: linux-arm-msm@vger.kernel.org, bbhatt@codeaurora.org References: <1606404547-10737-1-git-send-email-loic.poulain@linaro.org> <1606404547-10737-4-git-send-email-loic.poulain@linaro.org> <39fae2b9-cdde-1864-8ff3-55e3c07f4264@codeaurora.org> Message-ID: Date: Fri, 27 Nov 2020 10:40:41 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <39fae2b9-cdde-1864-8ff3-55e3c07f4264@codeaurora.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 11/27/2020 10:34 AM, Jeffrey Hugo wrote: > On 11/26/2020 8:29 AM, Loic Poulain wrote: >> Ensure that the device is hard-reset on remove to restore its initial >> state and avoid further issues on subsequent probe. >> >> This has been tested with Telit FN980m module. >> >> Signed-off-by: Loic Poulain >> --- >>   drivers/bus/mhi/pci_generic.c | 11 +++++++++++ >>   1 file changed, 11 insertions(+) >> >> diff --git a/drivers/bus/mhi/pci_generic.c >> b/drivers/bus/mhi/pci_generic.c >> index d3896ef..4363676 100644 >> --- a/drivers/bus/mhi/pci_generic.c >> +++ b/drivers/bus/mhi/pci_generic.c >> @@ -15,6 +15,8 @@ >>   #define MHI_PCI_DEFAULT_BAR_NUM 0 >> +#define DEV_RESET_REG (0xB0) >> + >>   /** >>    * struct mhi_pci_dev_info - MHI PCI device specific information >>    * @config: MHI controller configuration >> @@ -166,6 +168,11 @@ static void mhi_pci_status_cb(struct >> mhi_controller *mhi_cntrl, >>       /* Nothing to do for now */ >>   } >> +static inline void mhi_pci_reset(struct mhi_controller *mhi_cntrl) >> +{ >> +    writel(1, mhi_cntrl->regs + DEV_RESET_REG); >> +} >> + >>   static int mhi_pci_claim(struct mhi_controller *mhi_cntrl, >>                unsigned int bar_num, u64 dma_mask) >>   { >> @@ -329,6 +336,10 @@ static void mhi_pci_remove(struct pci_dev *pdev) >>       mhi_power_down(mhi_cntrl, true); >>       mhi_unprepare_after_power_down(mhi_cntrl); >>       mhi_unregister_controller(mhi_cntrl); >> + >> +    /* MHI-layer reset could not be enough, always hard-reset the >> device */ >> +    mhi_pci_reset(mhi_cntrl); >> + >>       mhi_free_controller(mhi_cntrl); >>   } >> > > Did you miss my eariler comment asking to make this functionality common? Sorry, I missed your reply to my reply. > > Also, I caution you to think carefully about this.  Its possible doing > this type of reset can take down the PCI link, and the host would need > to have PCI hotplug to recover.  If not, the device will become > inaccessable until the host reboots. > -- Jeffrey Hugo Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.