From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752758AbeBVIU4 (ORCPT ); Thu, 22 Feb 2018 03:20:56 -0500 Received: from mga06.intel.com ([134.134.136.31]:24105 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752628AbeBVIUy (ORCPT ); Thu, 22 Feb 2018 03:20:54 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.47,377,1515484800"; d="scan'208";a="206063299" Subject: Re: [RFC PATCH] mmc: sdhci-of-arasan: Add auto tuning support for ZynqMP Platform To: Manish Narani , "michal.simek@xilinx.com" , "ulf.hansson@linaro.org" , "linux-arm-kernel@lists.infradead.org" , "linux-mmc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "devicetree@vger.kernel.org" , "mark.rutland@arm.com" , "robh+dt@kernel.org" Cc: Anirudha Sarangi , Srinivas Goud References: <1517336073-18142-1-git-send-email-mnarani@xilinx.com> <608309c3-fc4d-25a2-f0a9-21c0f3e2db46@intel.com> From: Adrian Hunter Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki, Business Identity Code: 0357606 - 4, Domiciled in Helsinki Message-ID: Date: Thu, 22 Feb 2018 10:20:07 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 21/02/18 17:00, Manish Narani wrote: > Hi Adrian, > >> -----Original Message----- >> From: Manish Narani >> Sent: Wednesday, February 21, 2018 11:39 AM >> To: Adrian Hunter ; michal.simek@xilinx.com; >> ulf.hansson@linaro.org; linux-arm-kernel@lists.infradead.org; linux- >> mmc@vger.kernel.org; linux-kernel@vger.kernel.org; >> devicetree@vger.kernel.org; mark.rutland@arm.com; robh+dt@kernel.org >> Cc: Anirudha Sarangi ; Srinivas Goud >> >> Subject: RE: [RFC PATCH] mmc: sdhci-of-arasan: Add auto tuning support for >> ZynqMP Platform >> >> Hi Adrian, >> >> >>> -----Original Message----- >>> From: Adrian Hunter [mailto:adrian.hunter@intel.com] >>> Sent: Friday, February 16, 2018 7:37 PM >>> To: Manish Narani ; michal.simek@xilinx.com; >>> ulf.hansson@linaro.org; linux-arm-kernel@lists.infradead.org; linux- >>> mmc@vger.kernel.org; linux-kernel@vger.kernel.org; >>> devicetree@vger.kernel.org; mark.rutland@arm.com; robh+dt@kernel.org >>> Cc: Anirudha Sarangi ; Srinivas Goud >>> ; Manish Narani >>> Subject: Re: [RFC PATCH] mmc: sdhci-of-arasan: Add auto tuning support >>> for ZynqMP Platform >>> >>> On 30/01/18 20:14, Manish Narani wrote: >>>> This patch adds support of SD auto tuning for ZynqMP platform. Auto >>>> tuning sequence sends tuning block to card when operating in UHS-1 >>>> modes. This resets the DLL and sends CMD19/CMD21 as a part of the >>>> auto tuning process. Once the auto tuning process gets completed, >>>> reset the DLL to load the newly obtained SDHC tuned tap value. >>> >>> How is this different from: >>> 1. reset the dll >>> 2. call sdhci_execute_tuning >>> 3. reset the dll >>> > Below is my take on your above comments: > - 'Reset the dll' is a platform specific call inside 'arasan_zynqmp_execute_tuning' which is implemented in sdhci-of-arasan.c > - 'arasan_zynqmp_execute_tuning' is called from 'sdhci_execute_tuning' as a platform_execute_tuning routine > - So to keep 'DLL reset' routine called from sdhci-of-arasan.c, I have implemented the execute_tuning in sdhci-of-arasan.c I meant something like: if (of_device_is_compatible(pdev->dev.of_node, "xlnx,zynqmp-8.9a")) host->mmc_host_ops.execute_tuning = arasan_zynqmp_execute_tuning; static int arasan_zynqmp_execute_tuning(struct mmc_host *mmc, u32 opcode) { struct sdhci_host *host = mmc_priv(mmc); struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host); struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host); int err; arasan_zynqmp_dll_reset(host, sdhci_arasan->device_id); err = sdhci_execute_tuning(mmc, opcode); if (err) return err; arasan_zynqmp_dll_reset(host, sdhci_arasan->device_id); return 0; } > > Alternative way (Please review): > - Define a host->quirk2 bit (SDHCI_QUIRK2_DLL_RESET_NEEDED) in sdhci-of-arasan.c indicating DLL reset needed while tuning operation > - Call 'dll reset' routine before and after __sdhci_execute_tuning() in sdhci.c when a host->quirk2 bit (SDHCI_QUIRK2_DLL_RESET_NEEDED) is set We should try to avoid quirks.