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([2a01:e0a:982:cbb0:990a:74e6:266e:2294]) by smtp.gmail.com with ESMTPSA id t18-20020a5d5352000000b0031c3ee933b5sm3598140wrv.108.2023.09.14.23.56.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 14 Sep 2023 23:56:51 -0700 (PDT) Message-ID: <5cd2ed15-949d-40b4-93fd-b1480f557b14@linaro.org> Date: Fri, 15 Sep 2023 08:56:49 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Neil Armstrong Subject: Re: [PATCH tty v1 37/74] serial: meson: Use port lock wrappers Content-Language: en-US, fr To: John Ogness , Greg Kroah-Hartman Cc: Jiri Slaby , linux-serial@vger.kernel.org, Petr Mladek , Thomas Gleixner , linux-kernel@vger.kernel.org, Kevin Hilman , Jerome Brunet , Martin Blumenstingl , Dmitry Rokosov , Lucas Tanure , =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= , linux-arm-kernel@lists.infradead.org, linux-amlogic@lists.infradead.org References: <20230914183831.587273-1-john.ogness@linutronix.de> <20230914183831.587273-38-john.ogness@linutronix.de> Autocrypt: addr=neil.armstrong@linaro.org; keydata= xsBNBE1ZBs8BCAD78xVLsXPwV/2qQx2FaO/7mhWL0Qodw8UcQJnkrWmgTFRobtTWxuRx8WWP GTjuhvbleoQ5Cxjr+v+1ARGCH46MxFP5DwauzPekwJUD5QKZlaw/bURTLmS2id5wWi3lqVH4 BVF2WzvGyyeV1o4RTCYDnZ9VLLylJ9bneEaIs/7cjCEbipGGFlfIML3sfqnIvMAxIMZrvcl9 qPV2k+KQ7q+aXavU5W+yLNn7QtXUB530Zlk/d2ETgzQ5FLYYnUDAaRl+8JUTjc0CNOTpCeik 80TZcE6f8M76Xa6yU8VcNko94Ck7iB4vj70q76P/J7kt98hklrr85/3NU3oti3nrIHmHABEB AAHNKk5laWwgQXJtc3Ryb25nIDxuZWlsLmFybXN0cm9uZ0BsaW5hcm8ub3JnPsLAkQQTAQoA OwIbIwULCQgHAwUVCgkICwUWAgMBAAIeAQIXgBYhBInsPQWERiF0UPIoSBaat7Gkz/iuBQJk Q5wSAhkBAAoJEBaat7Gkz/iuyhMIANiD94qDtUTJRfEW6GwXmtKWwl/mvqQtaTtZID2dos04 YqBbshiJbejgVJjy+HODcNUIKBB3PSLaln4ltdsV73SBcwUNdzebfKspAQunCM22Mn6FBIxQ GizsMLcP/0FX4en9NaKGfK6ZdKK6kN1GR9YffMJd2P08EO8mHowmSRe/ExAODhAs9W7XXExw UNCY4pVJyRPpEhv373vvff60bHxc1k/FF9WaPscMt7hlkbFLUs85kHtQAmr8pV5Hy9ezsSRa GzJmiVclkPc2BY592IGBXRDQ38urXeM4nfhhvqA50b/nAEXc6FzqgXqDkEIwR66/Gbp0t3+r yQzpKRyQif3OwE0ETVkGzwEIALyKDN/OGURaHBVzwjgYq+ZtifvekdrSNl8TIDH8g1xicBYp QTbPn6bbSZbdvfeQPNCcD4/EhXZuhQXMcoJsQQQnO4vwVULmPGgtGf8PVc7dxKOeta+qUh6+ SRh3vIcAUFHDT3f/Zdspz+e2E0hPV2hiSvICLk11qO6cyJE13zeNFoeY3ggrKY+IzbFomIZY 4yG6xI99NIPEVE9lNBXBKIlewIyVlkOaYvJWSV+p5gdJXOvScNN1epm5YHmf9aE2ZjnqZGoM Mtsyw18YoX9BqMFInxqYQQ3j/HpVgTSvmo5ea5qQDDUaCsaTf8UeDcwYOtgI8iL4oHcsGtUX oUk33HEAEQEAAcLAXwQYAQIACQUCTVkGzwIbDAAKCRAWmrexpM/4rrXiB/sGbkQ6itMrAIfn M7IbRuiSZS1unlySUVYu3SD6YBYnNi3G5EpbwfBNuT3H8//rVvtOFK4OD8cRYkxXRQmTvqa3 3eDIHu/zr1HMKErm+2SD6PO9umRef8V82o2oaCLvf4WeIssFjwB0b6a12opuRP7yo3E3gTCS KmbUuLv1CtxKQF+fUV1cVaTPMyT25Od+RC1K+iOR0F54oUJvJeq7fUzbn/KdlhA8XPGzwGRy 4zcsPWvwnXgfe5tk680fEKZVwOZKIEuJC3v+/yZpQzDvGYJvbyix0lHnrCzq43WefRHI5XTT QbM0WUIBIcGmq38+OgUsMYu4NzLu7uZFAcmp6h8g Organization: Linaro Developer Services In-Reply-To: <20230914183831.587273-38-john.ogness@linutronix.de> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230914_235655_414696_4EBE56F8 X-CRM114-Status: GOOD ( 28.10 ) 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: , Reply-To: neil.armstrong@linaro.org 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 14/09/2023 20:37, John Ogness wrote: > From: Thomas Gleixner > > When a serial port is used for kernel console output, then all > modifications to the UART registers which are done from other contexts, > e.g. getty, termios, are interference points for the kernel console. > > So far this has been ignored and the printk output is based on the > principle of hope. The rework of the console infrastructure which aims to > support threaded and atomic consoles, requires to mark sections which > modify the UART registers as unsafe. This allows the atomic write function > to make informed decisions and eventually to restore operational state. It > also allows to prevent the regular UART code from modifying UART registers > while printk output is in progress. > > All modifications of UART registers are guarded by the UART port lock, > which provides an obvious synchronization point with the console > infrastructure. > > To avoid adding this functionality to all UART drivers, wrap the > spin_[un]lock*() invocations for uart_port::lock into helper functions > which just contain the spin_[un]lock*() invocations for now. In a > subsequent step these helpers will gain the console synchronization > mechanisms. > > Converted with coccinelle. No functional change. > > Signed-off-by: Thomas Gleixner > --- > drivers/tty/serial/meson_uart.c | 30 +++++++++++++++--------------- > 1 file changed, 15 insertions(+), 15 deletions(-) > > diff --git a/drivers/tty/serial/meson_uart.c b/drivers/tty/serial/meson_uart.c > index 790d910dafa5..45cc23e9e399 100644 > --- a/drivers/tty/serial/meson_uart.c > +++ b/drivers/tty/serial/meson_uart.c > @@ -129,14 +129,14 @@ static void meson_uart_shutdown(struct uart_port *port) > > free_irq(port->irq, port); > > - spin_lock_irqsave(&port->lock, flags); > + uart_port_lock_irqsave(port, &flags); > > val = readl(port->membase + AML_UART_CONTROL); > val &= ~AML_UART_RX_EN; > val &= ~(AML_UART_RX_INT_EN | AML_UART_TX_INT_EN); > writel(val, port->membase + AML_UART_CONTROL); > > - spin_unlock_irqrestore(&port->lock, flags); > + uart_port_unlock_irqrestore(port, flags); > } > > static void meson_uart_start_tx(struct uart_port *port) > @@ -238,7 +238,7 @@ static irqreturn_t meson_uart_interrupt(int irq, void *dev_id) > { > struct uart_port *port = (struct uart_port *)dev_id; > > - spin_lock(&port->lock); > + uart_port_lock(port); > > if (!(readl(port->membase + AML_UART_STATUS) & AML_UART_RX_EMPTY)) > meson_receive_chars(port); > @@ -248,7 +248,7 @@ static irqreturn_t meson_uart_interrupt(int irq, void *dev_id) > meson_uart_start_tx(port); > } > > - spin_unlock(&port->lock); > + uart_port_unlock(port); > > return IRQ_HANDLED; > } > @@ -284,7 +284,7 @@ static int meson_uart_startup(struct uart_port *port) > u32 val; > int ret = 0; > > - spin_lock_irqsave(&port->lock, flags); > + uart_port_lock_irqsave(port, &flags); > > val = readl(port->membase + AML_UART_CONTROL); > val |= AML_UART_CLEAR_ERR; > @@ -301,7 +301,7 @@ static int meson_uart_startup(struct uart_port *port) > val = (AML_UART_RECV_IRQ(1) | AML_UART_XMIT_IRQ(port->fifosize / 2)); > writel(val, port->membase + AML_UART_MISC); > > - spin_unlock_irqrestore(&port->lock, flags); > + uart_port_unlock_irqrestore(port, flags); > > ret = request_irq(port->irq, meson_uart_interrupt, 0, > port->name, port); > @@ -341,7 +341,7 @@ static void meson_uart_set_termios(struct uart_port *port, > unsigned long flags; > u32 val; > > - spin_lock_irqsave(&port->lock, flags); > + uart_port_lock_irqsave(port, &flags); > > cflags = termios->c_cflag; > iflags = termios->c_iflag; > @@ -401,7 +401,7 @@ static void meson_uart_set_termios(struct uart_port *port, > AML_UART_FRAME_ERR; > > uart_update_timeout(port, termios->c_cflag, baud); > - spin_unlock_irqrestore(&port->lock, flags); > + uart_port_unlock_irqrestore(port, flags); > } > > static int meson_uart_verify_port(struct uart_port *port, > @@ -460,14 +460,14 @@ static int meson_uart_poll_get_char(struct uart_port *port) > u32 c; > unsigned long flags; > > - spin_lock_irqsave(&port->lock, flags); > + uart_port_lock_irqsave(port, &flags); > > if (readl(port->membase + AML_UART_STATUS) & AML_UART_RX_EMPTY) > c = NO_POLL_CHAR; > else > c = readl(port->membase + AML_UART_RFIFO); > > - spin_unlock_irqrestore(&port->lock, flags); > + uart_port_unlock_irqrestore(port, flags); > > return c; > } > @@ -478,7 +478,7 @@ static void meson_uart_poll_put_char(struct uart_port *port, unsigned char c) > u32 reg; > int ret; > > - spin_lock_irqsave(&port->lock, flags); > + uart_port_lock_irqsave(port, &flags); > > /* Wait until FIFO is empty or timeout */ > ret = readl_poll_timeout_atomic(port->membase + AML_UART_STATUS, reg, > @@ -502,7 +502,7 @@ static void meson_uart_poll_put_char(struct uart_port *port, unsigned char c) > dev_err(port->dev, "Timeout waiting for UART TX EMPTY\n"); > > out: > - spin_unlock_irqrestore(&port->lock, flags); > + uart_port_unlock_irqrestore(port, flags); > } > > #endif /* CONFIG_CONSOLE_POLL */ > @@ -559,9 +559,9 @@ static void meson_serial_port_write(struct uart_port *port, const char *s, > if (port->sysrq) { > locked = 0; > } else if (oops_in_progress) { > - locked = spin_trylock(&port->lock); > + locked = uart_port_trylock(port); > } else { > - spin_lock(&port->lock); > + uart_port_lock(port); > locked = 1; > } > > @@ -573,7 +573,7 @@ static void meson_serial_port_write(struct uart_port *port, const char *s, > writel(val, port->membase + AML_UART_CONTROL); > > if (locked) > - spin_unlock(&port->lock); > + uart_port_unlock(port); > local_irq_restore(flags); > } > Acked-by: Neil Armstrong _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel