From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Cercueil Subject: Re: [PATCH 06/14] dmaengine: dma-jz4780: Add support for the JZ4725B SoC Date: Thu, 12 Jul 2018 01:13:55 +0200 Message-ID: <1531350835.2021.1@smtp.crapouillou.net> References: <20180703123214.23090-1-paul@crapouillou.net> <20180703123214.23090-7-paul@crapouillou.net> <20180709171458.GL22377@vkoul-mobl> <1531237502.17118.3@crapouillou.net> <20180711121818.GT3219@vkoul-mobl> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20180711121818.GT3219@vkoul-mobl> Sender: linux-kernel-owner@vger.kernel.org To: Vinod Cc: Rob Herring , Mark Rutland , Ralf Baechle , Paul Burton , James Hogan , Zubair Lutfullah Kakakhel , Mathieu Malaterre , Daniel Silsby , dmaengine@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mips@linux-mips.org List-Id: devicetree@vger.kernel.org Le mer. 11 juil. 2018 =E0 14:18, Vinod a =E9crit : > On 10-07-18, 17:45, Paul Cercueil wrote: >>=20 >>=20 >> Le lun. 9 juil. 2018 =E0 19:14, Vinod a =E9crit : >> > On 03-07-18, 14:32, Paul Cercueil wrote: >> > > The JZ4725B has one DMA core starring six DMA channels. >> > > As for the JZ4770, each DMA channel's clock can be enabled with >> > > a register write, the difference here being that once started,=20 >> it >> > > is not possible to turn it off. >> > >> > ok so disable for this, right.. >> > >> > > @@ -204,6 +205,8 @@ static inline void >> > > jz4780_dma_chan_enable(struct jz4780_dma_dev *jzdma, >> > > { >> > > if (jzdma->version =3D=3D ID_JZ4770) >> > > jz4780_dma_ctrl_writel(jzdma, JZ_DMA_REG_DCKES, BIT(chn)); >> > > + else if (jzdma->version =3D=3D ID_JZ4725B) >> > > + jz4780_dma_ctrl_writel(jzdma, JZ_DMA_REG_DCKE, BIT(chn)); >> > >> > but you are writing to a different register here.. >>=20 >> Yes. SoCs >=3D JZ4770 have the DCKE read-only register, and=20 >> DCKES/DCKEC to >> set/clear bits in DCKE. >> On JZ4725B, DCKE is read/write, but the zeros written are ignored=20 >> (at least >> that's what the >> documentation says). >=20 > and that was not documented in the log... so i though it maybe a typo. Right, I will add a comment in-code to explain that it's normal. > -- > ~Vinod Thanks, -Paul =