From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755660Ab1HEKFE (ORCPT ); Fri, 5 Aug 2011 06:05:04 -0400 Received: from eu1sys200aog107.obsmtp.com ([207.126.144.123]:47172 "EHLO eu1sys200aog107.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755586Ab1HEKFB (ORCPT ); Fri, 5 Aug 2011 06:05:01 -0400 From: Viresh Kumar To: , , Cc: , , , , , , , , , , , , , , Subject: [PATCH V3 16/20] dmaengine/amba-pl08x: Choose peripheral bus as master bus Date: Fri, 5 Aug 2011 15:32:41 +0530 Message-ID: X-Mailer: git-send-email 1.7.2.2 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When we have DMA transfers between peripheral and memory, then we shouldn't reduce width of peripheral at all, as that may be a strict requirement. But we can always reduce width of memory access, with some compromise in performance. Thus, we must select peripheral as master and not memory. Also this rearranges code to make it shorter. Signed-off-by: Viresh Kumar Acked-by: Linus Walleij --- drivers/dma/amba-pl08x.c | 22 ++++++---------------- 1 files changed, 6 insertions(+), 16 deletions(-) diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c index 4bcf603..f70aa57 100644 --- a/drivers/dma/amba-pl08x.c +++ b/drivers/dma/amba-pl08x.c @@ -499,34 +499,24 @@ struct pl08x_lli_build_data { * byte data), slave is still not aligned, then its width will be reduced to * BYTE. * - prefers the destination bus if both available - * - if fixed address on one bus the other will be chosen + * - prefers bus with fixed address (i.e. peripheral) */ static void pl08x_choose_master_bus(struct pl08x_lli_build_data *bd, struct pl08x_bus_data **mbus, struct pl08x_bus_data **sbus, u32 cctl) { if (!(cctl & PL080_CONTROL_DST_INCR)) { - *mbus = &bd->srcbus; - *sbus = &bd->dstbus; - } else if (!(cctl & PL080_CONTROL_SRC_INCR)) { *mbus = &bd->dstbus; *sbus = &bd->srcbus; + } else if (!(cctl & PL080_CONTROL_SRC_INCR)) { + *mbus = &bd->srcbus; + *sbus = &bd->dstbus; } else { - if (bd->dstbus.buswidth == 4) { - *mbus = &bd->dstbus; - *sbus = &bd->srcbus; - } else if (bd->srcbus.buswidth == 4) { - *mbus = &bd->srcbus; - *sbus = &bd->dstbus; - } else if (bd->dstbus.buswidth == 2) { + if (bd->dstbus.buswidth >= bd->srcbus.buswidth) { *mbus = &bd->dstbus; *sbus = &bd->srcbus; - } else if (bd->srcbus.buswidth == 2) { + } else { *mbus = &bd->srcbus; *sbus = &bd->dstbus; - } else { - /* bd->srcbus.buswidth == 1 */ - *mbus = &bd->dstbus; - *sbus = &bd->srcbus; } } } -- 1.7.2.2