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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 595CEC433EF for ; Wed, 20 Oct 2021 12:58:47 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 1C71161355 for ; Wed, 20 Oct 2021 12:58:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 1C71161355 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:Cc:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=zHN/xCvOQkWova0sOxV+IZrAeXQ3kBn75h3fZto6gHA=; b=PcV5/tzvaZyiTVn26+0GeudwaC R6mGvkUW6dZ7oibUOCwp/NPvj46Aqh1cpfvzkxHgmS7Xz4ydGaNPVcF1bzCCTS5uwH3Jzx0tyq/jm YcTDyxJaZl2hk3nDmkMgL1GvVovSwVfbsNRbhGftn04GBDWvlkVOSxiau3R9NGJ9HXDACuJ7JMXW3 IbmUG8LjONuW+2zh9CyT9XW/iO1hzNrrckc0KHd0mBf6Zkk2QGZ1S0zGUogbeymYb7ocrc5g3gCao JSwkF4jpQ1+oN+d0pWNxBCHec0czuC3HM+cB04E8uqgV6ZujyO+7c/GFN4xsKjcY+6Y3g/dvBBXMc ix1ZA4Pw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mdB9w-004Z9H-0v; Wed, 20 Oct 2021 12:57:32 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mdB9s-004Z8G-74; Wed, 20 Oct 2021 12:57:30 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5DD611FB; Wed, 20 Oct 2021 05:57:24 -0700 (PDT) Received: from [10.57.27.231] (unknown [10.57.27.231]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5A4933F73D; Wed, 20 Oct 2021 05:57:23 -0700 (PDT) Subject: Re: [PATCH] arm64: dts: rockchip: nanopi4: decrease Bluetooth UART baud rate To: wens@kernel.org, Heiko Stuebner Cc: linux-arm-kernel , "open list:ARM/Rockchip SoC..." , devicetree , linux-kernel References: <20210920175647.13008-1-wens@kernel.org> <64f06ddb-cde6-d71a-7920-41c485a1d3fb@arm.com> From: Robin Murphy Message-ID: Date: Wed, 20 Oct 2021 13:57:18 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211020_055728_422610_56513196 X-CRM114-Status: GOOD ( 38.65 ) 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2021-10-07 18:13, Chen-Yu Tsai wrote: > On Wed, Oct 6, 2021 at 6:49 PM Robin Murphy wrote: >> >> On 2021-09-20 18:56, Chen-Yu Tsai wrote: >>> From: Chen-Yu Tsai >>> >>> The RK3399 does not seem to be able to properly generate the required >>> 64 MHz clock for the UART to operate at 4MBd. >>> >>> Drop the baud rate down to 3MBd, which can be used as the clock >>> controller is able to produce a 48 MHz clock. >> >> Hmm, I've been running mine this way (with DMA) for ages now :/ > > I guess you have extra patches on top for DMA? I sent another patch > to hook up DMA. Indeed I've been using Katsuhiro's patch from ages ago: https://lore.kernel.org/linux-rockchip/20190321162244.10080-1-katsuhiro@katsuster.net/ Heiko - as far as I'm aware pl330 still isn't hooked up to virt-dma; I think the core change to avoid using DMA for the console UART has merely mitigated the issue by leaving just enough channels available for "most" use-cases. >> Looking at clk_summary, clk_uart0_src ends up at 800MHz off CPLL (same >> as several other significant clocks), with clk_uart0 at an exact 64MHz >> as a division of that. I stuck a scope on the UART pins of the module >> and all the edges look nicely lined up to 250ns intervals. > > Could you provide a partial dump of /sys/kernel/debug/clk/clk_summary ? > Just the bits related to uart0 should be enough. > > Mine is also running from CPLL, but ends up at 1843200 Hz, which seems > like the clock rate used for 115200 baud: > > xin24m 24 24 0 24000000 > 0 0 50000 Y > pll_cpll 1 1 0 800000000 > 0 0 50000 Y > cpll 7 15 0 800000000 > 0 0 50000 Y > clk_uart0_src 1 1 0 800000000 > 0 0 50000 Y > clk_uart0_div 1 1 0 800000000 > 0 0 50000 Y > clk_uart0_frac 1 1 0 1843200 > 0 0 50000 Y > clk_uart0 1 1 0 1843200 > 0 0 50000 Y > > I also observe a couple error messages: > > Bluetooth: hci0: BCM: failed to write clock (-56) > Bluetooth: hci0: Failed to set baudrate > Bluetooth: hci0: BCM: chip id 130 > Bluetooth: hci0: BCM: features 0x0f > Bluetooth: hci0: BCM4345C5 > Bluetooth: hci0: BCM4345C5 (003.006.006) build 0000 > Bluetooth: hci0: BCM4345C5 'brcm/BCM4345C5.hcd' Patch > Bluetooth: hci0: BCM: failed to write clock (-56) > Bluetooth: hci0: BCM4345C5 Ampak_CL1.5 UART 37.4 MHz BT 5.0 [Version: > Version: 0033.0080] > Bluetooth: hci0: BCM4345C5 (003.006.006) build 0080 > > So I think my UART is actually still running at its initial speed. FWIW, with a functioning 5.14 kernel back on my board (5.15-rc4 couldn't even boot due to eMMC issues), nothing stands out except the lack of errors. However, looking again at said errors and digging in to bcm_set_baudrate(), it looks like it's actually the module itself being unhappy about the special command to update *its* clock, which then prevents the host baud rate from being changed from its initial 115200. The internet leads me to believe that BCM4345C5 is BCM43455 which is now CYW43555 whose datasheet says "UART baud rates up to 4 Mbps", so whatever the issue is it looks to be beyond the limit of my knowledge. Poking around hci_bcm to see if there's any notable difference between the modules, I spotted commit e601daed271e mentioning issues with AP6256, so I wonder if using the "brcm,bcm4345c5" compatible as an override in the M4B DTS makes any difference? If not, now that things seem to make a bit more sense it might be reasonable to tweak the speed for M4B as a workaround to avoid sending the offending command (since AP6356S as used on the other variants seems unaffected), unless Bluetooth people can shed any more light on why the module is unhappy about it. Cheers, Robin. > Another thing is that the Rockchip datasheet says something about the > denominator has to be 20 times larger than the nominator for a stable clock. > >> This is with a 5.11.4 kernel, though - I wonder if the recent fractional >> divider changes in the clock driver have changed anything? > > I tried reverting the three patches but that didn't make a difference. > > Regards > ChenYu > > >> >>> Fixes: 3e2f0bb72be3 ("arm64: dts: rockchip: Add nanopi4 bluetooth") >>> Signed-off-by: Chen-Yu Tsai >>> --- >>> arch/arm64/boot/dts/rockchip/rk3399-nanopi4.dtsi | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/arch/arm64/boot/dts/rockchip/rk3399-nanopi4.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-nanopi4.dtsi >>> index 8c0ff6c96e03..45ff053b119d 100644 >>> --- a/arch/arm64/boot/dts/rockchip/rk3399-nanopi4.dtsi >>> +++ b/arch/arm64/boot/dts/rockchip/rk3399-nanopi4.dtsi >>> @@ -699,7 +699,7 @@ bluetooth { >>> device-wakeup-gpios = <&gpio2 RK_PD2 GPIO_ACTIVE_HIGH>; >>> host-wakeup-gpios = <&gpio0 RK_PA4 GPIO_ACTIVE_HIGH>; >>> shutdown-gpios = <&gpio0 RK_PB1 GPIO_ACTIVE_HIGH>; >>> - max-speed = <4000000>; >>> + max-speed = <3000000>; >>> pinctrl-names = "default"; >>> pinctrl-0 = <&bt_reg_on_h &bt_host_wake_l &bt_wake_l>; >>> vbat-supply = <&vcc3v3_sys>; >>> _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel