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Wed, 02 Dec 2020 03:17:15 -0800 Received: from MTKMBS31N1.mediatek.inc (172.27.4.69) by MTKMBS62N2.mediatek.inc (172.29.193.42) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 2 Dec 2020 03:07:15 -0800 Received: from MTKCAS36.mediatek.inc (172.27.4.186) by MTKMBS31N1.mediatek.inc (172.27.4.69) with Microsoft SMTP Server (TLS) id 15.0.1497.2; Wed, 2 Dec 2020 19:06:41 +0800 Received: from [10.17.3.153] (10.17.3.153) by MTKCAS36.mediatek.inc (172.27.4.170) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Wed, 2 Dec 2020 19:06:40 +0800 Message-ID: <1606907202.14806.65.camel@mhfsdcap03> Subject: Re: [v6, 3/3] reset-controller: ti: force the write operation when assert or deassert From: Crystal Guo To: Ikjoon Jang Date: Wed, 2 Dec 2020 19:06:42 +0800 In-Reply-To: <20201130111340.GA3042402@chromium.org> References: <20200930022159.5559-1-crystal.guo@mediatek.com> <20200930022159.5559-4-crystal.guo@mediatek.com> <20201130111340.GA3042402@chromium.org> X-Mailer: Evolution 3.10.4-0ubuntu2 MIME-Version: 1.0 X-TM-SNTS-SMTP: 30A9654AF1CD9EA4FBA4BE9BFA52EA70554F9FC4BBB7FB01E220F307C0ED74462000:8 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201202_061727_283198_79374E37 X-CRM114-Status: GOOD ( 22.93 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "devicetree@vger.kernel.org" , Yong Liang =?UTF-8?Q?=28=E6=A2=81=E5=8B=87=29?= , "s-anna@ti.com" , srv_heupstream , Seiya Wang =?UTF-8?Q?=28=E7=8E=8B=E8=BF=BA=E5=90=9B=29?= , "linux-kernel@vger.kernel.org" , Fan Chen =?UTF-8?Q?=28=E9=99=B3=E5=87=A1=29?= , "robh+dt@kernel.org" , "linux-mediatek@lists.infradead.org" , "p.zabel@pengutronix.de" , "matthias.bgg@gmail.com" , Yingjoe Chen =?UTF-8?Q?=28=E9=99=B3=E8=8B=B1=E6=B4=B2=29?= , Stanley Chu =?UTF-8?Q?=28=E6=9C=B1=E5=8E=9F=E9=99=9E=29?= , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org On Mon, 2020-11-30 at 19:13 +0800, Ikjoon Jang wrote: > On Wed, Sep 30, 2020 at 10:21:59AM +0800, Crystal Guo wrote: > > Force the write operation in case the read already happens > > to return the correct value. > > > > Signed-off-by: Crystal Guo > > --- > > drivers/reset/reset-ti-syscon.c | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/reset/reset-ti-syscon.c b/drivers/reset/reset-ti-syscon.c > > index 5d1f8306cd4f..c34394f1e9e2 100644 > > --- a/drivers/reset/reset-ti-syscon.c > > +++ b/drivers/reset/reset-ti-syscon.c > > @@ -97,7 +97,7 @@ static int ti_syscon_reset_assert(struct reset_controller_dev *rcdev, > > mask = BIT(control->assert_bit); > > value = (control->flags & ASSERT_SET) ? mask : 0x0; > > > > - return regmap_update_bits(data->regmap, control->assert_offset, mask, value); > > + return regmap_write_bits(data->regmap, control->assert_offset, mask, value); > > } > > I don't think there are no reset controllers with cached regmap, > thus I don't think this is needed. > Are there any specific reasons behind this, what I've missed here? > > We need to be sure that all other devices using this driver > should have no side effects on write. > > I can think of a weird controller doing unwanted things internally > on every write disregarding the current state. (or is this overly > paranoid?) > The specific reason is that, the clear bit may keep the same value with the set bit, but the clear operation can be only be completed by writing 1 to the clear bit, not just with the current fake state "1". > > > > /** > > @@ -128,7 +128,7 @@ static int ti_syscon_reset_deassert(struct reset_controller_dev *rcdev, > > mask = BIT(control->deassert_bit); > > value = (control->flags & DEASSERT_SET) ? mask : 0x0; > > > > - return regmap_update_bits(data->regmap, control->deassert_offset, mask, value); > > + return regmap_write_bits(data->regmap, control->deassert_offset, mask, value); > > } > > > > /** _______________________________________________ Linux-mediatek mailing list Linux-mediatek@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-mediatek