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x-originating-ip: [89.37.124.34] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 66bdf910-1ee7-404d-563e-08d726fd0c3b x-ms-office365-filtering-ht: Tenant x-microsoft-antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(5600166)(711020)(4605104)(1401327)(4618075)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(2017052603328)(7193020);SRVR:VI1PR04MB5871; x-ms-traffictypediagnostic: VI1PR04MB5871: x-ms-exchange-transport-forked: True x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:7691; x-forefront-prvs: 01371B902F x-forefront-antispam-report: SFV:NSPM;SFS:(10009020)(4636009)(346002)(366004)(396003)(376002)(39860400002)(136003)(189003)(199004)(305945005)(5660300002)(76116006)(66946007)(66446008)(64756008)(66556008)(66476007)(14454004)(53936002)(8676002)(102836004)(6246003)(66066001)(9686003)(478600001)(446003)(316002)(33656002)(7736002)(53546011)(6506007)(2906002)(54906003)(71200400001)(256004)(476003)(3846002)(6116002)(25786009)(7696005)(186003)(110136005)(52536014)(81166006)(6436002)(86362001)(76176011)(14444005)(44832011)(99286004)(74316002)(55016002)(486006)(2501003)(4326008)(71190400001)(8936002)(81156014)(26005)(229853002);DIR:OUT;SFP:1101;SCL:1;SRVR:VI1PR04MB5871;H:VI1PR04MB7023.eurprd04.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;MX:1;A:1; received-spf: None (protection.outlook.com: nxp.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: ggsv6HV2BmM0wgmKqg1eNwIeYNfWZL6jwA3ih7GrZMDDmzT8nWWmQD93BDHZ908o6bYLxiYBDjIEQ5hqDwrDbhAikhdH8XyvqM6XK4DvkVUuKSpZ20wVAcmEU+pUHycgJuHHYWj1sh5vKmOK+AJDZqUQsVks9XNz0SIrIaGaw79UXa1v83cpz3S9UtVKk7azvEt5atwj2QyfXVDMg6MWByrw94IqaiwfIlj2d72O0kMb9ws8ScTsj/xFDZKkwdC7nYyMQK1bPvKQrZzXgejtds9oioC4j5hXnRXWlhbaZcEB+A3jRyZrgPjrTeZ981aEII5r6toDcK7wmbtEuw/vEwd4hv4EPxCgZipHpddGy1QCSwctFkVH/wWecNl7IXPiAzb6HAaMmrFIO/1gEP8qkU1B1NG/FqY0KW0pGtko4PU= Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nxp.com X-MS-Exchange-CrossTenant-Network-Message-Id: 66bdf910-1ee7-404d-563e-08d726fd0c3b X-MS-Exchange-CrossTenant-originalarrivaltime: 22 Aug 2019 12:34:16.8389 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: dUyg9FnkptF2eQD2A3+brWjj5IZN/Vj0yiQwwVg8scDxqVg2LtOS9/kdq3SCUkWauc/9nkezu9VGhCtcVlKNZA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR04MB5871 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22.08.2019 12:18, Peng Fan wrote:=0A= >> Subject: Re: [PATCH] clk: imx: pll14xx: avoid glitch when set rate=0A= >>=0A= >> On 20.08.2019 05:17, Peng Fan wrote:=0A= >>> According to PLL1443XA and PLL1416X spec, "When BYPASS is 0 and RESETB= =0A= >>> is changed from 0 to 1, FOUT starts to output unstable clock until=0A= >>> lock time passes. PLL1416X/PLL1443XA may generate a glitch at FOUT."=0A= >>>=0A= >>> So set BYPASS when RESETB is changed from 0 to 1 to avoid glitch.=0A= >>> In the end of set rate, BYPASS will be cleared.=0A= >>>=0A= >>> @@ -191,6 +191,10 @@ static int clk_pll1416x_set_rate(struct clk_hw *hw= ,=0A= >> unsigned long drate,=0A= >>> tmp &=3D ~RST_MASK;=0A= >>> writel_relaxed(tmp, pll->base);=0A= >>>=0A= >>> + /* Enable BYPASS */=0A= >>> + tmp |=3D BYPASS_MASK;=0A= >>> + writel(tmp, pll->base);=0A= >>> +=0A= >>=0A= >> Shouldn't BYPASS be set before reset?=0A= > =0A= > No. the glitch happens when RESET changes from 0 to 1, not from 1 to 0.= =0A= =0A= You're right, sorry.=0A= =0A= >> Also, isn't a similar bypass/unbypass dance also needed in=0A= >> clk_pll14xx_prepare? As far as I understand that could also output glitc= hes=0A= >> until the PLL is locked. It could be a separate patch.=0A= > =0A= > Yes, that might also output glitch. Fix in v2.=0A= > =0A= >>=0A= >> It's strange that this BYPASS bit is also handled by muxes like=0A= >> audio_pll1_bypass in clk-imx8mm.c but that's a separate issue not strict= ly=0A= >> related to the glitches you're trying to fix here.=0A= > =0A= > Yes, need use EXT_BYPASS for the mux usage.=0A= =0A= Might make sense to post as a series.=0A=