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 C2740566C for ; Thu, 9 Nov 2023 03:47:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tEdF27pk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D9FD2C433C7; Thu, 9 Nov 2023 03:47:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699501653; bh=SWhjJ7hhv9wUwqxTduJwGa1UjeUMqMhHmLc00yZI2UE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=tEdF27pk6HCPeWqdWutrT2VL5TCOV1t1BGdbD03A2hdCz2ryxX2P+n0jr4dwRj61G 6jo5Ks8YERqKV3//Can0w7/eJQy8oEIPdBrpWdmNnZvIgJFC5Mj0S28fDo1UYDUi/c x4ve6uGVTxP+vDCHqGb50asCoCbEvDYZ7qsj1Vf/HychKLNraKqpJar8G5CCDo7KpJ +xAHyXO3u20eT12Re+GdQJyr9hsqavj7vSNTNFB/YZFEI1f4Wa7xzftR7F09Nu6BeV 6iUW7Lp4/bZJF9VRJ2KcDj3gSqqh42XV6TkEhnaIKK3UBPa9CA1AO4n4pAAr9VyQzO JRopHU2ZPbZ5Q== Date: Thu, 9 Nov 2023 09:17:17 +0530 From: Manivannan Sadhasivam To: Can Guo Cc: Can Guo , bvanassche@acm.org, stanley.chu@mediatek.com, adrian.hunter@intel.com, beanhuo@micron.com, avri.altman@wdc.com, junwoo80.lee@samsung.com, martin.petersen@oracle.com, linux-scsi@vger.kernel.org, Andy Gross , Bjorn Andersson , Konrad Dybcio , "James E.J. Bottomley" , "open list:ARM/QUALCOMM SUPPORT" , open list Subject: Re: [PATCH v2 3/7] scsi: ufs: ufs-qcom: Allow the first init start with the maximum supported gear Message-ID: <20231109034717.GD3752@thinkpad> References: <1699332374-9324-1-git-send-email-cang@qti.qualcomm.com> <1699332374-9324-4-git-send-email-cang@qti.qualcomm.com> <20231108052310.GC3296@thinkpad> <49b331dc-37eb-6e26-f701-c83187a30788@quicinc.com> Precedence: bulk X-Mailing-List: linux-arm-msm@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: <49b331dc-37eb-6e26-f701-c83187a30788@quicinc.com> On Wed, Nov 08, 2023 at 04:21:52PM +0800, Can Guo wrote: > Hi Mani, > > On 11/8/2023 1:23 PM, Manivannan Sadhasivam wrote: > > On Mon, Nov 06, 2023 at 08:46:09PM -0800, Can Guo wrote: > > > From: Can Guo > > > > > > During host driver init, the phy_gear is set to the minimum supported gear > > > (HS_G2). Then, during the first power mode change, the negotiated gear, say > > > HS-G4, is updated to the phy_gear variable so that in the second init the > > > updated phy_gear can be used to program the PHY. > > > > > > But the current code only allows update the phy_gear to a higher value. If > > > one wants to start the first init with the maximum support gear, say HS-G4, > > > the phy_gear is not updated to HS-G3 if the device only supports HS-G3. > > > > > > > Can you elaborate when this can happen? AFAICS, there are 3 possibilities of > > initial phy gear with this series: > > > > 1. If ufshc is < 5.0, then G2 will be used. > > 2. If ufshc is >= 5.0 and if the version is populated in register, then that > > gear will be used. Most likely that gear can be G4/G5 depending on the device > > connected. > > 3. If ufshc is >=5.0 and version is not populated, then G4 will be used. > > > > In all the above cases, I do not see any necessity to switch the phy gear > > setting to lower one while scaling. Since the gears are backwards compatible, > > we always use one phy gear sequence. Moreover, we only have 2 init sequences. > > > > Please correct me if I'm missing anything. > > > > - Mani > In the next patch, I am setting the initial PHY gear to max HS gear read > from UFS host cap register, so that we don't need to keep updating the > initial value for host->phy_gear for different HW versions in future. FYI, > for HW ver 5 and 6, it is HS-G5. In future, the max gear might become HS-G6 > or higher on newer HW verions. > > I the case #3, if HS-G5 is set to host->phy_gear, the first init uses HS-G5, > then after negotiation if the agreed gear is HS-G4, we need to update > host->phy_gear to HS-G4 (a lower value) such that we use a power saving PHY > gear settings during the 2nd init. > > If the commit message is making you confused, I can update it in next > version. Please let me if I made any mistakes here. > I see redundancy while setting the phy_gear and it is leading to confusion. In ufs_qcom_set_host_params(), first you are setting phy_gear based on ufs_qcom_get_hs_gear(), then changing it again with the version check for v5. I don't see a necessity for "host->phy_gear = host_params->hs_tx_gear", since in the later check, you are covering both version <5 and >=5. Btw, it would be better to move this logic to a separate function like ufs_qcom_get_phy_gear() to align with ufs_qcom_get_hs_gear(). - Mani > Thanks, > Can Guo. -- மணிவண்ணன் சதாசிவம்