Messages in this thread | | | Date | Wed, 24 Aug 2022 10:44:43 +0300 | From | "Ivan T. Ivanov" <> | Subject | Re: [PATCH v3] clk: bcm2835: Round UART input clock up |
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On 08-23 16:08, Stephen Boyd wrote: > Date: Tue, 23 Aug 2022 16:08:40 -0700 > From: Stephen Boyd <sboyd@kernel.org> > To: Albert Ou <aou@eecs.berkeley.edu>, Broadcom internal kernel review list > <bcm-kernel-feedback-list@broadcom.com>, Florian Fainelli > <f.fainelli@gmail.com>, "Ivan T. Ivanov" <iivanov@suse.de>, Michael > Turquette <mturquette@baylibre.com>, Nicolas Saenz Julienne > <nsaenz@kernel.org>, Palmer Dabbelt <palmer@dabbelt.com>, Paul Walmsley > <paul.walmsley@sifive.com>, Ray Jui <rjui@broadcom.com>, Scott Branden > <sbranden@broadcom.com>, Stefan Wahren <stefan.wahren@i2se.com> > Cc: "Ivan T. Ivanov" <iivanov@suse.de>, Phil Elwell <phil@raspberrypi.org>, > kernel test robot <lkp@intel.com>, linux-clk@vger.kernel.org, > linux-rpi-kernel@lists.infradead.org, > linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, > linux-riscv@lists.infradead.org > Subject: Re: [PATCH v3] clk: bcm2835: Round UART input clock up > Message-Id: <20220823230842.AB8BAC433C1@smtp.kernel.org> > > Quoting Ivan T. Ivanov (2022-05-27 03:29:00) > > It was reported that RPi3[1] and RPi Zero 2W boards have issues with > > the Bluetooth. It turns out that when switching from initial to > > operation speed host and device no longer can talk each other because > > host uses incorrect UART baud rate. > > > > The UART driver used in this case is amba-pl011. Original fix, see > > below Github link[2], was inside pl011 module, but somehow it didn't > > look as the right place to fix. Beside that this original rounding > > function is not exactly perfect for all possible clock values. So I > > deiced to move the hack to the platform which actually need it. > > > > The UART clock is initialised to be as close to the requested > > frequency as possible without exceeding it. Now that there is a > > clock manager that returns the actual frequencies, an expected > > 48MHz clock is reported as 47999625. If the requested baud rate > > == requested clock/16, there is no headroom and the slight > > reduction in actual clock rate results in failure. > > > > If increasing a clock by less than 0.1% changes it from ..999.. > > to ..000.., round it up. > > > > [1] https://bugzilla.suse.com/show_bug.cgi?id=1188238 > > [2] https://github.com/raspberrypi/linux/commit/ab3f1b39537f6d3825b8873006fbe2fc5ff057b7 > > > > Cc: Phil Elwell <phil@raspberrypi.org> > > Signed-off-by: Ivan T. Ivanov <iivanov@suse.de> > > --- > > This is waiting for someone like Stefan to review. It's customary to > include previous reviewers on new versions of patches.
Thanks for fixing me mistake.
Regards, Ivan
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