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([179.179.238.247]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-36081bafa7asm39596320eec.14.2026.10.20.03.48.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Oct 2026 03:48:04 -0700 (PDT) From: Vinicius Pedrosa To: Andy Shevchenko Cc: linux-serial@vger.kernel.org, gregkh@linuxfoundation.org, jirislaby@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, ilpo.jarvinen@linux.intel.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev, Andre Przywara , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland , Enzo Adriano , stable@vger.kernel.org Subject: Re: [PATCH v2 1/4] serial: 8250_dw: Keep the BUSY-safe divisor hook when DLF is present Date: Tue, 20 Oct 2026 07:47:53 -0300 Message-ID: <20261020104753.28703-1-vinicius.eduardo.pedrosa@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi Andy, On Tue, 20 Oct 2026, Andy Shevchenko wrote: > > + /* Keep a hook the driver has already installed */ > > + if (!p->set_divisor) > > + p->set_divisor = dw8250_set_divisor; > > On top of my previous reply, why is this hunk needed? dw8250_probe() installs the BUSY-safe dw8250_set_divisor() before dw8250_setup_port() runs. Without the !p->set_divisor check, detecting DLF replaces it with the dwlib setter, which is the BUSY problem described in the commit message. > In the case of existing _set_divisor, do we want to keep the possible set > _get_divisor as well? Shouldn't we introduce a respective _get_divisor in > 8250_dw.c? 8250_dw.c doesn't install a get_divisor, so there's no existing getter to preserve. The dwlib getter is still needed when DLF is present, because it computes the fractional part used by the preserved BUSY-safe setter. > But now I see that we have same function name in two files. Can we rename > those in dwlib to, for example, > dw8250_get_divisor --> dw8250_get_dfl_divisor > dw8250_set_divisor --> dw8250_set_dfl_divisor I'll also clean up the naming in v3: dw8250_update_dlf() with a frac parameter, static inline after dw8250_writel_ext(), and the dwlib-local helpers renamed to dw8250_get_dlf_divisor() and dw8250_set_dlf_divisor(). Thanks, Vinicius