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Wed, 19 Feb 2020 02:35:29 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 26925C43383; Wed, 19 Feb 2020 02:35:29 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: cang) by smtp.codeaurora.org (Postfix) with ESMTPSA id 90523C433A2; Wed, 19 Feb 2020 02:35:27 +0000 (UTC) MIME-Version: 1.0 Date: Wed, 19 Feb 2020 10:35:27 +0800 From: Can Guo To: Stanley Chu Subject: Re: [PATCH v1 1/2] scsi: ufs: add required delay after gating reference clock In-Reply-To: <56c1fc80919491d058d904fcc7301835@codeaurora.org> References: <20200217093559.16830-1-stanley.chu@mediatek.com> <20200217093559.16830-2-stanley.chu@mediatek.com> <1581945168.26304.4.camel@mtksdccf07> <1581946449.26304.15.camel@mtksdccf07> <56c1fc80919491d058d904fcc7301835@codeaurora.org> Message-ID: X-Sender: cang@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200218_183530_627660_B8E45BC1 X-CRM114-Status: GOOD ( 18.85 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-scsi@vger.kernel.org, martin.petersen@oracle.com, andy.teng@mediatek.com, jejb@linux.ibm.com, chun-hung.wu@mediatek.com, kuohong.wang@mediatek.com, linux-kernel@vger.kernel.org, avri.altman@wdc.com, linux-mediatek@lists.infradead.org, peter.wang@mediatek.com, alim.akhtar@samsung.com, matthias.bgg@gmail.com, asutoshd@codeaurora.org, bvanassche@acm.org, linux-arm-kernel@lists.infradead.org, beanhuo@micron.com Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Stanely, On 2020-02-17 21:42, Can Guo wrote: > On 2020-02-17 21:34, Stanley Chu wrote: >> Hi Can, >> >> On Mon, 2020-02-17 at 21:22 +0800, Can Guo wrote: >>> On 2020-02-17 21:12, Stanley Chu wrote: >>> > Hi Can, >>> > >>> > >>> >> > } else if (!on && clki->enabled) { >>> >> > clk_disable_unprepare(clki->clk); >>> >> > + wait_us = hba->dev_info.clk_gating_wait_us; >>> >> > + if (ref_clk && wait_us) >>> >> > + usleep_range(wait_us, wait_us + 10); >>> >> >>> >> Hi St,anley, >>> >> >>> >> If wait_us is 1us, it would be inappropriate to use usleep_range() >>> >> here. >>> >> You have checks of the delay in patch #2, but why it is not needed >>> >> here? >>> >> >>> >> Thanks, >>> >> Can Guo. >>> > >>> > You are right. I could make that delay checking as common function so >>> > it >>> > can be used here as well to cover all possible values. >>> > >>> > Thanks for suggestion. >>> > Stanley >>> >>> Hi Stanley, >>> >>> One more thing, as in patch #2, you have already added delays in your >>> ufshcd_vops_setup_clocks(OFF, PRE_CHANGE) path, plus this delay here, >>> don't you delay for 2*bRefClkGatingWaitTime in ufshcd_setup_clocks()? >>> As the delay added in your vops also delays the actions of turning >>> off all the other clocks in ufshcd_setup_clocks(), you don't need the >>> delay here again, do you agree? >> >> MediaTek driver is not using reference clocks named as "ref_clk" >> defined >> in device tree, thus the delay specific for "ref_clk" in >> ufshcd_setup_clocks() will not be applied in MediaTek platform. >> >> This patch is aimed to add delay for this kind of "ref_clk" used by >> any >> future vendors. >> >> Anyway thanks for the reminding : ) >> >>> >>> Thanks, >>> Can Guo. >> >> >> Thanks, >> Stanley > > Hi Stanley, > > Then we are unluckily hit by this change. We have ref_clk in DT, thus > this change would add unwanted delays to our platforms. but still we > disable device's ref_clk in vops. :) > > Could you please hold on patch #1 first? I need sometime to have a > dicussion with my colleagues on this. > > Thanks. > Can Guo. Since we all need this delay here, how about put the delay in the entrence of ufshcd_setup_clocks(), before vops_setup_clocks()? If so, we can remove all the delays we added in our vops since the delay anyways delays everything inside ufshcd_setup_clocks(). Meanwhile, if you want to modify the delay (hba->dev_info.clk_gating_wait_us) for some reasons, say for specific UFS devices, you still can do it in vops_apply_dev_quirks(). What do you say? Thanks, Can Guo. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel