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Mon, 17 Feb 2020 13:42:37 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id AB308C4479C; Mon, 17 Feb 2020 13:42:36 +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 E4707C43383; Mon, 17 Feb 2020 13:42:35 +0000 (UTC) MIME-Version: 1.0 Date: Mon, 17 Feb 2020 21:42:35 +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: <1581946449.26304.15.camel@mtksdccf07> 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> Message-ID: <56c1fc80919491d058d904fcc7301835@codeaurora.org> 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-20200217_054245_290506_EEBEF3D6 X-CRM114-Status: GOOD ( 17.99 ) 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 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. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel