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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=VE3Ea4BPCkopgR+SceHAr1CcKWEjirXXxv6I5VlDKz0=; b=IQCK45akHrpGDa5Zh9/WksBlzuLW4Jb1RU77EV52tkM0q3yNtsa7y7fVul/0Y4AL2C WzswacD1svh/D7S63O4qMoHee8MI14YGrOtI1wYa0m9/FvwBUR/0ZHYPpf3ZVnwDL289 84x/y2vRqediAGffCck26u3AKdgdbO+R4HyjH+scTIwA6aDyb8EtMz3yj2Arcq00CCwg Dy1ZecR4uiWTfDrO+cv9ymnOI1TfKDMTUkOc5u4p2bJkM2flyar2pRPb9kFMPjk2/XXv NAhiUSh5RGrDtsniNUqTNYvw/nME5CmDw93bVZ9TPFA7PIkFID2O1K9RmpLN9hutH7Qv QD5A== X-Gm-Message-State: AOAM533Oym08sxBHEDTXVhfDlN080tBezavAIMGnRuBIJoWSpmOM9oEt gbpf4oTH/qEuiI/aLf4xfpG9s7IWw2By9yFQA+Q= X-Google-Smtp-Source: ABdhPJwlhXn1ZUS4AdM5ajJYAe3cfRVYfAgGzqYz3WTPupXpBrrnVxTMG5QmLY1S1tVt2GhIwlmiJFWoIa91wRifW6I= X-Received: by 2002:a17:907:7789:: with SMTP id ky9mr6329024ejc.191.1624259762466; Mon, 21 Jun 2021 00:16:02 -0700 (PDT) MIME-Version: 1.0 References: <20210617194154.2397-1-linux.amoon@gmail.com> <20210617194154.2397-7-linux.amoon@gmail.com> In-Reply-To: From: Anand Moon Date: Mon, 21 Jun 2021 12:45:51 +0530 Message-ID: Subject: Re: [RFCv1 6/8] phy: amlogic: meson8b-usb2: Use phy reset callback function To: Martin Blumenstingl Cc: Kishon Vijay Abraham I , Vinod Koul , Neil Armstrong , Kevin Hilman , Jerome Brunet , Philipp Zabel , linux-phy@lists.infradead.org, linux-arm-kernel , linux-amlogic@lists.infradead.org, Linux Kernel X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210621_001604_075234_6032DA3A X-CRM114-Status: GOOD ( 26.98 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Martin Thanks for your review comments. On Sat, 19 Jun 2021 at 01:36, Martin Blumenstingl wrote: > > Hi Anand, > > On Fri, Jun 18, 2021 at 5:33 PM Anand Moon wrote: > [...] > > > For shared resets (like the one we have here) reset_control_reset will > > > only trigger the reset line once until all drivers using that reset > > > line are unloaded. > > > So effectively this new phy_ops.reset callback will be a no-op. > > > > I know his register is shared between two USB IPs, > > but I have not observed any issues. > have you checked at which point we're then actually triggering the reset? > I assume that you will find that the reset is only triggered for the > very first power_on/init call - which makes this patch effectively a > no-op (yes, we're calling reset_control_reset then, but that doesn't > mean that a reset is triggered on hardware level - see > drivers/reset/core.c at around line 346). > Ok Thanks for the inputs. got your point. I was also looking into Amlogic source code for reset. (aml_cbus_update_bits) [0] https://github.com/khadas/linux/blob/khadas-vims-4.9.y/drivers/amlogic/usb/phy/phy-aml-new-usb.c is there some feature to iomap the USB with cbus? > [...] > > > > - priv->reset = devm_reset_control_get_optional_shared(&pdev->dev, NULL); > > > > + priv->reset = devm_reset_control_get_optional_shared(&pdev->dev, "phy"); > > > I think this breaks compatibility with existing .dtbs and our > > > dt-bindings (as we're not documenting a "reset-names" property). > > > What is the goal of this one? > > > > > > > OK, If we pass NULL over here there is the possibility > > USB phy will not get registered. > I don't understand why - with NULL everything is working fine for me. > Also no matter which name you give to the reset line (in reset-names), > it will be the same reset line in all cases. If it's the same reset > line before and after: why is this needed? > I need to investigate this reset feature. With my setup with current changes after I update the below. - priv->reset = devm_reset_control_get_optional_shared(&pdev->dev, "phy"); + priv->reset = devm_reset_control_get_optional_shared(&pdev->dev, NULL); if (PTR_ERR(priv->reset) == -EPROBE_DEFER) return PTR_ERR(priv->reset); Reset will break the USB initialization, see below output. [ 1.265403] dwc2 c9040000.usb: mapped PA c9040000 to VA (ptrval) [ 1.265540] dwc2 c9040000.usb: Looking up vusb_d-supply from device tree [ 1.265554] dwc2 c9040000.usb: Looking up vusb_d-supply property in node /soc/usb@c9040000 failed [ 1.265585] dwc2 c9040000.usb: supply vusb_d not found, using dummy regulator [ 1.265717] dwc2 c9040000.usb: Looking up vusb_a-supply from device tree [ 1.265730] dwc2 c9040000.usb: Looking up vusb_a-supply property in node /soc/usb@c9040000 failed [ 1.265752] dwc2 c9040000.usb: supply vusb_a not found, using dummy regulator [ 1.265812] dwc2 c9040000.usb: registering common handler for irq35 [ 1.265867] dwc2 c9040000.usb: Looking up vbus-supply from device tree [ 1.265880] dwc2 c9040000.usb: Looking up vbus-supply property in node /soc/usb@c9040000 failed [ 1.267066] dwc2 c9040000.usb: Core Release: 3.10a (snpsid=4f54310a) [ 1.270983] dwc2 c9040000.usb: dwc2_core_reset: HANG! Soft Reset timeout GRSTCTL_CSFTRST [ 1.271319] dwc2: probe of c9040000.usb failed with error -16 [ 1.273296] dwc2 c90c0000.usb: mapped PA c90c0000 to VA (ptrval) [ 1.273426] dwc2 c90c0000.usb: Looking up vusb_d-supply from device tree [ 1.273440] dwc2 c90c0000.usb: Looking up vusb_d-supply property in node /soc/usb@c90c0000 failed [ 1.273471] dwc2 c90c0000.usb: supply vusb_d not found, using dummy regulator [ 1.273607] dwc2 c90c0000.usb: Looking up vusb_a-supply from device tree [ 1.273621] dwc2 c90c0000.usb: Looking up vusb_a-supply property in node /soc/usb@c90c0000 failed [ 1.273641] dwc2 c90c0000.usb: supply vusb_a not found, using dummy regulator [ 1.273700] dwc2 c90c0000.usb: registering common handler for irq36 [ 1.273750] dwc2 c90c0000.usb: Looking up vbus-supply from device tree [ 1.273762] dwc2 c90c0000.usb: Looking up vbus-supply property in node /soc/usb@c90c0000 failed [ 1.274966] dwc2 c90c0000.usb: Core Release: 3.10a (snpsid=4f54310a) [ 1.278888] dwc2 c90c0000.usb: dwc2_core_reset: HANG! Soft Reset timeout GRSTCTL_CSFTRST [ 1.279224] dwc2: probe of c90c0000.usb failed with error -16 > > Best regards, > Martin Thanks -Anand _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel