From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752780AbcLCIyO (ORCPT ); Sat, 3 Dec 2016 03:54:14 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:44574 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751401AbcLCIyL (ORCPT ); Sat, 3 Dec 2016 03:54:11 -0500 DMARC-Filter: OpenDMARC Filter v1.3.1 smtp.codeaurora.org C8B2760218 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=pass smtp.mailfrom=riteshh@codeaurora.org Subject: Re: [PATCH v2] mmc: sdhci-msm: Add sdhci_reset() implementation To: Georgi Djakov References: <20161128173920.25334-1-georgi.djakov@linaro.org> <27e95224-ff32-954d-443a-2310c1225ca0@codeaurora.org> <7f35faac-7c04-8024-3111-9d4742ad2154@linaro.org> Cc: adrian.hunter@intel.com, ulf.hansson@linaro.org, linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org From: Ritesh Harjani Message-ID: Date: Sat, 3 Dec 2016 14:24:04 +0530 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <7f35faac-7c04-8024-3111-9d4742ad2154@linaro.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/1/2016 11:38 PM, Georgi Djakov wrote: > On 11/29/2016 05:40 AM, Ritesh Harjani wrote: >> Hi Georgi, >> >> On 11/28/2016 11:09 PM, Georgi Djakov wrote: >>> On apq8016, apq8084 and apq8074 platforms, writing to the software >>> reset register triggers the "power irq". We need to ack and handle >>> the irq, otherwise the following message appears: >>> >>> mmc0: Reset 0x1 never completed. >>> sdhci: =========== REGISTER DUMP (mmc0)=========== >>> sdhci: Sys addr: 0x00000000 | Version: 0x00002e02 >>> sdhci: Blk size: 0x00004000 | Blk cnt: 0x00000000 >>> sdhci: Argument: 0x00000000 | Trn mode: 0x00000000 >>> sdhci: Present: 0x01f80000 | Host ctl: 0x00000000 >>> sdhci: Power: 0x00000000 | Blk gap: 0x00000000 >>> sdhci: Wake-up: 0x00000000 | Clock: 0x00000003 >>> sdhci: Timeout: 0x00000000 | Int stat: 0x00000000 >>> sdhci: Int enab: 0x00000000 | Sig enab: 0x00000000 >>> sdhci: AC12 err: 0x00000000 | Slot int: 0x00000000 >>> sdhci: Caps: 0x322dc8b2 | Caps_1: 0x00008007 >>> sdhci: Cmd: 0x00000000 | Max curr: 0x00000000 >>> sdhci: Host ctl2: 0x00000000 >>> sdhci: ADMA Err: 0x00000000 | ADMA Ptr: 0x0000000000000000 >>> sdhci: =========================================== >>> >>> Fix it by implementing the custom sdhci_reset() function, >>> which performs the software reset and then handles the irq. >>> >>> Signed-off-by: Georgi Djakov >>> --- >>> >>> Changes since v1: (https://lkml.org/lkml/2016/11/22/411) >>> * Perform the software reset by just writing to the >>> SDHCI_SOFTWARE_RESET >>> register and then check for the irq. >> I am still not sure about this change. Below change will trigger the >> IRQ, once this call is completed (say on a single core system) -since >> this is called while holding spin_lock_irqsave. >> >> But you will be end up calling sdhci_msm_voltage_switch twice, >> which to me does not seems correct. >> 1. 1st time you are directly calling it in sdhci_msm_reset. >> 2. 2nd time will be called from within pwr_irq to handle the same case. > > Yes, that would be the behavior. This function actually is not doing > anything much than to check irq status and ack it. Testing the patch Ok. > on a few different platforms does not show any side effects, however i > could not be 100% sure as i have limited information about the hardware. what about the case when say the IRQ is delayed because of some other overheads in the system. Will this approach still works? I understand this would require some HW knowledge to understand the functioning/importance of this pwr_irq. I will try and get in touch with HW folk here. Regards Ritesh > > Thanks, > Georgi > >> >> Please let me know your thoughts on this ? >> >> Regards >> Ritesh >> >>> >>> drivers/mmc/host/sdhci-msm.c | 29 ++++++++++++++++++++++++++++- >>> 1 file changed, 28 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/mmc/host/sdhci-msm.c b/drivers/mmc/host/sdhci-msm.c >>> index 32879b845b75..157ae07f9309 100644 >>> --- a/drivers/mmc/host/sdhci-msm.c >>> +++ b/drivers/mmc/host/sdhci-msm.c >>> @@ -1019,6 +1019,33 @@ static void sdhci_msm_set_clock(struct >>> sdhci_host *host, unsigned int clock) >>> __sdhci_msm_set_clock(host, clock); >>> } >>> >>> +void sdhci_msm_reset(struct sdhci_host *host, u8 mask) >>> +{ >>> + unsigned long timeout = 100; >>> + >>> + sdhci_writeb(host, mask, SDHCI_SOFTWARE_RESET); >>> + >>> + if (mask & SDHCI_RESET_ALL) { >>> + host->clock = 0; >>> + >>> + /* >>> + * SDHCI_RESET_ALL triggers the PWR IRQ and we need >>> + * to handle it here. >>> + */ >>> + sdhci_msm_voltage_switch(host); >>> + } >>> + >>> + while (sdhci_readb(host, SDHCI_SOFTWARE_RESET) & mask) { >>> + if (timeout == 0) { >>> + pr_err("%s: Reset 0x%x never completed.\n", >>> + mmc_hostname(host->mmc), (int)mask); >>> + return; >>> + } >>> + timeout--; >>> + mdelay(1); >>> + } >>> +} >>> + >>> static const struct of_device_id sdhci_msm_dt_match[] = { >>> { .compatible = "qcom,sdhci-msm-v4" }, >>> {}, >>> @@ -1028,7 +1055,7 @@ MODULE_DEVICE_TABLE(of, sdhci_msm_dt_match); >>> >>> static const struct sdhci_ops sdhci_msm_ops = { >>> .platform_execute_tuning = sdhci_msm_execute_tuning, >>> - .reset = sdhci_reset, >>> + .reset = sdhci_msm_reset, >>> .set_clock = sdhci_msm_set_clock, >>> .get_min_clock = sdhci_msm_get_min_clock, >>> .get_max_clock = sdhci_msm_get_max_clock, >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-mmc" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >> > -- > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project