From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heikki Krogerus Subject: [PATCH 4/4] serial: 8250_dw: Set maxburst size Date: Wed, 16 Jan 2013 14:08:16 +0200 Message-ID: <1358338096-32081-5-git-send-email-heikki.krogerus@linux.intel.com> References: <1358338096-32081-1-git-send-email-heikki.krogerus@linux.intel.com> Return-path: Received: from mga09.intel.com ([134.134.136.24]:29833 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753859Ab3APMHV (ORCPT ); Wed, 16 Jan 2013 07:07:21 -0500 In-Reply-To: <1358338096-32081-1-git-send-email-heikki.krogerus@linux.intel.com> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Greg Kroah-Hartman Cc: Alan Cox , linux-serial@vger.kernel.org The default burst is often 1 byte which is not very optimal. The ideal burst size when using 16550A type port would be 1/2 of fifosize, but this does not work with all Designware implementations. Setting it to 1/4 fifosize. Signed-off-by: Heikki Krogerus --- drivers/tty/serial/8250/8250_dw.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index bfdaf8b..117bb8b 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -178,6 +178,7 @@ dw8250_acpi_walk_resource(struct acpi_resource *res, void *data) slave->direction = DMA_MEM_TO_DEV; slave->dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; slave->slave_id = fixed_dma->request_lines; + slave->dst_maxburst = port->tx_loadsz / 4; dma->tx_chan_id = fixed_dma->channels; dma->tx_param = &dma->tx_chan_id; @@ -189,6 +190,7 @@ dw8250_acpi_walk_resource(struct acpi_resource *res, void *data) slave->direction = DMA_DEV_TO_MEM; slave->src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE; slave->slave_id = fixed_dma->request_lines; + slave->src_maxburst = p->fifosize / 4; dma->rx_chan_id = fixed_dma->channels; dma->rx_param = &dma->rx_chan_id; @@ -296,6 +298,8 @@ static int dw8250_probe(struct platform_device *pdev) uart.port.serial_in = dw8250_serial_in; uart.port.serial_out = dw8250_serial_out; + dw8250_setup_port(&uart); + if (pdev->dev.of_node) { err = dw8250_probe_of(&uart.port); if (err) @@ -308,8 +312,6 @@ static int dw8250_probe(struct platform_device *pdev) return -ENODEV; } - dw8250_setup_port(&uart); - data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); if (!data) return -ENOMEM; -- 1.7.10.4