From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adrian Hunter Subject: Re: [RFC PATCH] mmc: sdhci-of-arasan: Add auto tuning support for ZynqMP Platform Date: Thu, 22 Feb 2018 10:20:07 +0200 Message-ID: References: <1517336073-18142-1-git-send-email-mnarani@xilinx.com> <608309c3-fc4d-25a2-f0a9-21c0f3e2db46@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org 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: Srinivas Goud , Anirudha Sarangi List-Id: devicetree@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.