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[72.77.81.136]) by smtp.gmail.com with ESMTPSA id s8-20020a05620a254800b006fa16fe93bbsm8449105qko.15.2022.11.15.08.26.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Nov 2022 08:26:07 -0800 (PST) Date: Tue, 15 Nov 2022 11:26:05 -0500 From: "Gabriel L. Somlo" To: Ilpo =?iso-8859-1?Q?J=E4rvinen?= Cc: LKML , linux-serial , Greg Kroah-Hartman , Jiri Slaby , kgugala@antmicro.com, mholenko@antmicro.com, joel@jms.id.au, david.abdurachmanov@gmail.com, florent@enjoy-digital.fr, geert@linux-m68k.org Subject: Re: [PATCH v3 12/14] serial: liteuart: add IRQ support for the RX path Message-ID: References: <20221112212125.448824-1-gsomlo@gmail.com> <20221112212125.448824-13-gsomlo@gmail.com> <7b5042be-8061-d4f4-43b5-75a5ad6dbcb0@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7b5042be-8061-d4f4-43b5-75a5ad6dbcb0@linux.intel.com> X-Clacks-Overhead: GNU Terry Pratchett Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 15, 2022 at 06:21:00PM +0200, Ilpo Järvinen wrote: > On Tue, 15 Nov 2022, Gabriel L. Somlo wrote: > > > On Tue, Nov 15, 2022 at 06:00:11PM +0200, Ilpo Järvinen wrote: > > > On Sat, 12 Nov 2022, Gabriel Somlo wrote: > > > > > > > Add support for IRQ-driven RX. Support for the TX path will be added > > > > in a separate commit. > > > > > > > > Signed-off-by: Gabriel Somlo > > > > --- > > > > drivers/tty/serial/liteuart.c | 61 +++++++++++++++++++++++++++++++---- > > > > 1 file changed, 54 insertions(+), 7 deletions(-) > > > > > > > > diff --git a/drivers/tty/serial/liteuart.c b/drivers/tty/serial/liteuart.c > > > > index cf1ce597b45e..e30adb30277f 100644 > > > > --- a/drivers/tty/serial/liteuart.c > > > > +++ b/drivers/tty/serial/liteuart.c > > > > @@ -6,6 +6,7 @@ > > > > */ > > > > > > > > #include > > > > +#include > > > > #include > > > > #include > > > > #include > > > > @@ -130,13 +131,29 @@ static void liteuart_rx_chars(struct uart_port *port) > > > > tty_flip_buffer_push(&port->state->port); > > > > } > > > > > > > > +static irqreturn_t liteuart_interrupt(int irq, void *data) > > > > +{ > > > > + struct liteuart_port *uart = data; > > > > + struct uart_port *port = &uart->port; > > > > + u8 isr = litex_read8(port->membase + OFF_EV_PENDING); > > > > + > > > > + /* for now, only rx path triggers interrupts */ > > > > > > Please don't add comment like this at all when your series removes it in a > > > later patch. > > > > OK, I will remove it in v4. > > > > > > + isr &= EV_RX; > > > > + > > > > + spin_lock(&port->lock); > > > > + if (isr & EV_RX) > > > > + liteuart_rx_chars(port); > > > > + spin_unlock(&port->lock); > > > > + > > > > + return IRQ_RETVAL(isr); > > > > +} > > > > + > > > > static void liteuart_timer(struct timer_list *t) > > > > { > > > > struct liteuart_port *uart = from_timer(uart, t, timer); > > > > struct uart_port *port = &uart->port; > > > > > > > > - liteuart_rx_chars(port); > > > > - > > > > + liteuart_interrupt(0, port); > > > > mod_timer(&uart->timer, jiffies + uart_poll_timeout(port)); > > > > } > > > > > > > > @@ -162,19 +179,42 @@ static unsigned int liteuart_get_mctrl(struct uart_port *port) > > > > static int liteuart_startup(struct uart_port *port) > > > > { > > > > struct liteuart_port *uart = to_liteuart_port(port); > > > > + int ret; > > > > + u8 irq_mask = 0; > > > > > > > > - /* disable events */ > > > > - litex_write8(port->membase + OFF_EV_ENABLE, 0); > > > > + if (port->irq) { > > > > + ret = request_irq(port->irq, liteuart_interrupt, 0, > > > > + KBUILD_MODNAME, uart); > > > > + if (ret == 0) { > > > > + /* only enable rx interrupts at this time */ > > > > > > This comment seems pretty useless. Your code says very much the same. > > > > The comment was meant to let the reader know that the code is doing it > > *intentionally* (rather than forgetting to enable tx irqs by mistake). > > But I'm OK with removing this comment in v4 as well if you think > > that's an overly paranoid and redundant thing to do... :) > > I see. Reading the other comment first caused me to misinterpret this one > to mean that only RX interrupts are implemented. > > Maybe if you change "at this time" to "at startup" it would make it more > obvious. OK, I'll fix the comment per your suggestion rather than get rid of it. Thanks again, --G > -- > i.