From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E57B7C02194 for ; Fri, 7 Feb 2025 02:29:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=4xfkBHNnNfhnAk+NPVOb8AHFgB+axQL5PKulKsKTDgk=; b=pEBw6X1txnhqA3U9+DKaJGMV6Q 8L8WR0XBficd7AhNXDtv3BZkYY7yfZF0zP2BE6Pcf6m8NBfUeJC9lHIz/1RhBl3IwxHImODiCPEpk Fr+k1dybKSKeU2l+Lc8PF4ZK4UaRr2U0I9OdSxqPGSbqrXD8+hxSmucl2afyvxac7oA6IKkpi/oMZ QWPh3MjQOXPSPJVm38dsBseH1PRslgVyGWWCNsdoO5XeVWPqztwUhlu4Ng1Q1YLViJdN/29ukjUR6 I1ED94IZLP6LyohwaMQDgezCu7z6GAFrlwVqob+sTbM+nGdouA/7bWw3GHojdFnOPwETWNwWXGw8B EpSp9kAg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tgE75-000000085R7-1Y9p; Fri, 07 Feb 2025 02:29:03 +0000 Received: from nyc.source.kernel.org ([2604:1380:45d1:ec00::3]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tgE3i-0000000852j-1qPA for linux-arm-kernel@lists.infradead.org; Fri, 07 Feb 2025 02:25:35 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id 66955A44B0A; Fri, 7 Feb 2025 02:23:47 +0000 (UTC) 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250206125943.786949-1-s-vadapalli@ti.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250206_182534_604092_D97CFACE X-CRM114-Status: GOOD ( 25.62 ) 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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