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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=915jr1GvJqW/XnIrI3t1cz5Ff5V+KSrPiSwAsvPilYA=; b=STgio7hBB7zkBKUof489vyRGm8NAVPjMgJiiZKRkHGUNsPlcOgDhOcpH3b+R5Ocd3p 8oP/wLmnPruQyG/y5JLa8yartvi+tdnPTyYyo4Zz1exGguEY6BV25z1yzeQQR7ZYrasB 64CAwLA3ZIqXVHfVu0VQ7SPqop3bULO+/AoXHtjUnX6qWmtpMcWwj7yClwQwNU7s9bxM boJjVIeBV8VQVhoNXZuzq6YuHcSEaWpWIhPiuxxy9f/xx24X4nzdX7nd1MhehzrDfjo6 asnuj3aCw0vFe5DKq4ByWnAZZ8wZG9W9+1BSEODumRXoLQNoEfL9K2jd78dXudK8Iw6D HXeQ== X-Gm-Message-State: APjAAAWhnzXGFiq+8zTWDqj7zppjLCQpsCWup+unsvmXT4xxEfPZUU6h 3H3zjsb/YUcuakTJXclbvMvLYIBK73V/uc0eUNAee54p X-Google-Smtp-Source: APXvYqza8rWHidcHCCjVSBTPT+5lCJioVNWdyCZbW7cNHRuU9UZiZ+nqv4uprd5V5nvKK7gywSHHdFQ5iv3dyS8WUXM= X-Received: by 2002:a6b:4107:: with SMTP id n7mr7372020ioa.12.1562901930907; Thu, 11 Jul 2019 20:25:30 -0700 (PDT) MIME-Version: 1.0 References: <20190609055658.3446-1-andrew.smirnov@gmail.com> In-Reply-To: <20190609055658.3446-1-andrew.smirnov@gmail.com> From: Andrey Smirnov Date: Thu, 11 Jul 2019 20:25:19 -0700 Message-ID: Subject: Re: [PATCH] i2c: imx: Initialize DMA before registering I2C adapter To: Wolfram Sang X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190711_202532_348992_CF2C8A08 X-CRM114-Status: GOOD ( 12.22 ) 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-kernel , linux-i2c@vger.kernel.org, Chris Healy , Fabio Estevam , linux-arm-kernel , NXP Linux Team Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sat, Jun 8, 2019 at 10:57 PM Andrey Smirnov wrote: > > Allocating DMA after registering I2C adapter can lead to infinite > probing loop, for example, consider the following scenario: > > 1. i2c_imx_probe() is called and successfully registers an I2C > adapter via i2c_add_numbered_adapter() > > 2. As a part of i2c_add_numbered_adapter() new I2C slave devices > are added from DT which results in a call to > driver_deferred_probe_trigger() > > 3. i2c_imx_probe() continues and calls i2c_imx_dma_request() which > due to lack of proper DMA driver returns -EPROBE_DEFER > > 4. i2c_imx_probe() fails, removes I2C adapter and returns > -EPROBE_DEFER, which places it into deferred probe list > > 5. Deferred probe work triggered in #2 above kicks in and calls > i2c_imx_probe() again thus bringing us to step #1 > > To avoid having this problem, move i2c_imx_dma_request() to happen > before i2c_add_numbered_adapter(). > > This problem was encountered on VF610 CFU1 board with > CONFIG_FSL_EDMA=n. > > Signed-off-by: Andrey Smirnov > Cc: Chris Healy > Cc: Wolfram Sang > Cc: Fabio Estevam > Cc: NXP Linux Team > Cc: linux-i2c@vger.kernel.org > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org Gentle ping. Any feedback on this? Thanks, Andrey Smirnov _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel