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 AADD017BA6; Sat, 8 Feb 2025 05:39:54 +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=1738993195; cv=none; b=EKdQVm9opc30OH2n5t9+nZjOdXPNRlH/gqmZ5E1EIRO8zYWDmANqPGDPatk+eMYwjmzQ6A9ExWQKgYDpQZ52kJCHarU77Uu1iT+bR+FpIRBBZCxNMMDHLPqruBwdRYLM/5NxUQ34EKFIdrCCbmGIgSAWBjQdyeaRuqxTGtGWhTI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738993195; c=relaxed/simple; bh=EIO2RApIMTaoQHu0AYGuzLxcnzfiMUbPkQ+Ttz9uEII=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=bezvMdVPi36fGf/NACaf7GAR/fnOWukpvgaCBdmM/uzREP7m951Eqa3VGg+lQD5skLg1YFN4isN60Iclq94A7+Y5pGgImaKYhH9X4XCrv4wRWil8hX6zndKvXMwo5Gp+a2McAgSjbJSS4GLdOwXM06ep+YajPjHxyR20Vd1vgVY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=S7IS+KGI; 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="S7IS+KGI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1A947C4CED6; Sat, 8 Feb 2025 05:39:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1738993194; bh=EIO2RApIMTaoQHu0AYGuzLxcnzfiMUbPkQ+Ttz9uEII=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=S7IS+KGI3Cu01/xSeKZlmjbimenl4l3+vdhqWbdTyYouNNAUtuuQyWwiHKVab3XdB IB8DBjZoyV7v0hhgNXxbff/mQ4HWs+m6zW94oGZB5LRvd4hYLwvkeeoIn3ilJEvi6r d5sR38oZnjxCT2bzT+5w4IMqQAl2yyowhLtQ14Cx4wgFbu/70jSYWyPIo+/4ANPurY K2Vsydclww71WiA2sgAFS235YE0a/UI72AZy008IOfcGiw/Mo7tN8/zXACsW96UHkI R6JA0YGDChkYHuY3eC0/8hCSicNYgXRy9TDwA71pP8+0ttdS7ftm/K4BaU25IZCoPJ n/1jziYmSveFg== Date: Sat, 8 Feb 2025 13:39:44 +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: <20250208053944.GA28062@nchen-desktop> References: <20250206125943.786949-1-s-vadapalli@ti.com> <20250207022523.GA22848@nchen-desktop> 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: On 25-02-07 11:12:50, Siddharth Vadapalli wrote: > On Fri, Feb 07, 2025 at 10:25:23AM +0800, Peter Chen wrote: > > Hello Peter, > > > 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? > > I did think of that initially, but the problem with doing so is that we > are already accessing USB_CONF above in the "switch(max_speed)" section. > The PUSB_PWR_FST_REG_ACCESS bit needs to be set before accessing any of: > - EP_CFG > - EP_TRADDR > - EP_CMD > - EP_SEL > - EP_STS > - USB_CONF > > Please let me know if you have an alternate suggestion to address the > above. > How about move cdns3_gadget_config at the beginning of function cdns3_gadget_udc_start, and add your changes at cdns3_gadget_config? Regards, Peter