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Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170711_033740_435890_B8A42DAC X-CRM114-Status: GOOD ( 17.50 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "moderated list:H8/300 ARCHITECTURE" , Rich Felker , Yoshinori Sato , Geert Uytterhoeven , Kevin Hilman , Linux-sh list , Magnus Damm , Linux-Renesas , Simon Horman , Laurent Pinchart , Olof Johansson , "linux-arm-kernel@lists.infradead.org" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP On 07/11/2017 03:59 AM, Geert Uytterhoeven wrote: > Hi Arnd, > > On Tue, Jul 11, 2017 at 10:42 AM, Arnd Bergmann wrote: >> On Tue, Jul 11, 2017 at 8:59 AM, Geert Uytterhoeven >> wrote: >>> On Tue, Jul 11, 2017 at 5:38 AM, Magnus Damm wrote: >>>> On Mon, Jul 10, 2017 at 10:28 PM, Geert Uytterhoeven >>>> Since enabling DMA Engine still keeps PIO support around I wonder why >>>> we need this Kconfig at all - other drivers seem to get by without >>>> this kind of thing? >>>> So in my opinion it would also be nice to get rid of SERIAL_SH_SCI_DMA >>>> completely and reducing the number of special per-driver Kconfig >>>> entries. >>> >>> In general, I would agree, and remove the option at the blimp of an eye. >>> However, this driver is shared with H8/300 and SuperH. While both could use >>> DMA (but it's not supported by Linux yet), I don't know if they are willing to >>> live with the increased static and dynamic memory footprint of SH_SCI DMA >>> support. >> >> One more thing: enabling the DMA support in the console driver generally >> means you cannot use printk in the DMA driver anywhere that may be called >> during printk(). Not sure if that is a concern here. > > Not anymore, as all of these prints should have been removed/disabled already. Last I checked qemu-system-sh4 still doesn't work with current linux serial driver unless you do: Does this DMA stuff make that situation worse? Rob --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -2193,7 +2193,7 @@ static void sci_reset(struct uart_port *port) setup_timer(&s->rx_fifo_timer, rx_fifo_timer_fn, (unsigned long)s); } else { - if (port->type == PORT_SCIFA || + if (1 || port->type == PORT_SCIFA || port->type == PORT_SCIFB) scif_set_rtrg(port, 1); else