From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 95E152940B; Fri, 7 Feb 2025 02:25:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738895133; cv=none; b=SMBotkaoiN8beUmxJ9j2VCP0jKWRqp/uRqLb9d9ULCN5h5WouGA7MGi2hA6+h90Pt+YQ8mHREOkHX/VPcSQbrR49AR2IpEoqjsL5uJwpTscM/ivpi8juGQtVR4/j/Kt3oYJDpxv01vvKT+gr/Zx+oC3WXTf3inFO0PbE5moCCys= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738895133; c=relaxed/simple; bh=O19jyvsGHqWSGaKQKD2496HsMxSWIhf1biOH4whG3x0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Q7VBuQ+3Ke+YY1POyo/bREjAjELbajQwRtxENOOFTaLEu+hdtr0KMM816a9mcnuhzByyBJJEWCvu8tOneY4NHOEP2kq6Fr0HcGHpJeDtO5M5CIV3sTsldqGIBw4dmSUjgAPKyyl4Ptp5+v1O7WVZV3eSQ/UGItPN9SGSbEdTnj8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Mg81V0AF; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Mg81V0AF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 56F8BC4CEDD; Fri, 7 Feb 2025 02:25:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1738895133; bh=O19jyvsGHqWSGaKQKD2496HsMxSWIhf1biOH4whG3x0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Mg81V0AFzNqlLXufz6dZLoe/3L46leDO3mLZO8/31BU39J0EjYvtJ8S5c4716uDTY d9ndYowId6BWt/WubqUhpYnQ7cTx8hLic47al6XjRHmJQNvF+Jcfgf+vRmvh5v4xZH 9jYR0/pFYucasHTWIZw9JjMub7QIhDMyL6ZWxeKnkgjU/poBd+/7dH0ZmJlOu+4NIG F6MyqeYX1R9s48C9SEdNJ7gRz9U23lq14c3zsyTXf/OPe0QOoFGVTnpO63TZBWsOIq 6GBvj8FcJleDnKC9V3BIwtdhpJcSBWhe0Rrl3KhDNr+rgA9LouS6qZ6Zq6CwK9yBX3 gf1yyH1n7rX+g== Date: Fri, 7 Feb 2025 10:25:23 +0800 From: Peter Chen To: Siddharth Vadapalli Cc: pawell@cadence.com, rogerq@kernel.org, gregkh@linuxfoundation.org, balbi@kernel.org, jun.li@nxp.com, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux-arm-kernel@lists.infradead.org, srk@ti.com Subject: Re: [PATCH] usb: cdns3: exit cdns3_gadget_udc_start if FAST_REG_ACCESS cannot be set Message-ID: <20250207022523.GA22848@nchen-desktop> References: <20250206125943.786949-1-s-vadapalli@ti.com> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250206125943.786949-1-s-vadapalli@ti.com> On 25-02-06 18:29:36, Siddharth Vadapalli wrote: > When the device is in a low power state, access to the following > registers takes a long time: > - EP_CFG > - EP_TRADDR > - EP_CMD > - EP_SEL > - EP_STS > - USB_CONF > > To address this, the fast register access feature can be enabled by > setting PUSB_PWR_FST_REG_ACCESS bit of the USB_PWR register, which > allows quick access by software. Software is expected to poll on > PUSB_PWR_FST_REG_ACCESS_STAT to ensure that fast register access has > been enabled by the controller. Attempting to access any of the > aforementioned registers after setting PUSB_PWR_FST_REG_ACCESS but > before PUSB_PWR_FST_REG_ACCESS_STAT has been set will result in > undefined behavior and potentially result in system hang. > > Hence, poll on PUSB_PWR_FST_REG_ACCESS_STAT before proceeding with > gadget configuration, and exit if it cannot be enabled. > > Fixes: b5148d946f45 ("usb: cdns3: gadget: set fast access bit") > Cc: > Signed-off-by: Siddharth Vadapalli > --- > > Hello, > > This patch is based on commit > 92514ef226f5 Merge tag 'for-6.14-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux > of Mainline Linux. > > Regards, > Siddharth. > > drivers/usb/cdns3/cdns3-gadget.c | 18 ++++++++++++++++-- > 1 file changed, 16 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c > index fd1beb10bba7..b62691944272 100644 > --- a/drivers/usb/cdns3/cdns3-gadget.c > +++ b/drivers/usb/cdns3/cdns3-gadget.c > @@ -2971,8 +2971,6 @@ static void cdns3_gadget_config(struct cdns3_device *priv_dev) > /* enable generic interrupt*/ > writel(USB_IEN_INIT, ®s->usb_ien); > writel(USB_CONF_CLK2OFFDS | USB_CONF_L1DS, ®s->usb_conf); > - /* keep Fast Access bit */ > - writel(PUSB_PWR_FST_REG_ACCESS, &priv_dev->regs->usb_pwr); > > cdns3_configure_dmult(priv_dev, NULL); > } > @@ -2990,6 +2988,8 @@ static int cdns3_gadget_udc_start(struct usb_gadget *gadget, > struct cdns3_device *priv_dev = gadget_to_cdns3_device(gadget); > unsigned long flags; > enum usb_device_speed max_speed = driver->max_speed; > + int ret; > + u32 reg; > > spin_lock_irqsave(&priv_dev->lock, flags); > priv_dev->gadget_driver = driver; > @@ -2997,6 +2997,20 @@ static int cdns3_gadget_udc_start(struct usb_gadget *gadget, > /* limit speed if necessary */ > max_speed = min(driver->max_speed, gadget->max_speed); > > + /* keep Fast Access bit */ > + writel(PUSB_PWR_FST_REG_ACCESS, &priv_dev->regs->usb_pwr); > + reg = readl(&priv_dev->regs->usb_pwr); > + if (!(reg & PUSB_PWR_FST_REG_ACCESS_STAT)) { > + ret = readl_poll_timeout_atomic(&priv_dev->regs->usb_pwr, reg, > + (reg & PUSB_PWR_FST_REG_ACCESS_STAT), > + 10, 1000); > + if (ret) { > + dev_err(priv_dev->dev, "Failed to enable fast access\n"); > + spin_unlock_irqrestore(&priv_dev->lock, flags); > + return ret; > + } > + } > + > switch (max_speed) { > case USB_SPEED_FULL: > writel(USB_CONF_SFORCE_FS, &priv_dev->regs->usb_conf); Hi Siddharth, Would you please keep this change at cdns3_gadget_config in case the controller is power lost during the system suspend? Peter