From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grant Likely Subject: Re: [PATCH v1] spi: davinci: Support DMA transfers larger than 65535 words Date: Mon, 14 Mar 2011 13:18:22 -0600 Message-ID: <20110314191822.GC16096@angua.secretlab.ca> References: <1300117742-1832-1-git-send-email-michael.williamson@criticallink.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, davinci-linux-open-source-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org, dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Michael Williamson Return-path: Content-Disposition: inline In-Reply-To: <1300117742-1832-1-git-send-email-michael.williamson-wZX4cNJlHJ2sVWG7oymsAA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: davinci-linux-open-source-bounces-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org Errors-To: davinci-linux-open-source-bounces-VycZQUHpC/PFrsHnngEfi1aTQe2KTcn/@public.gmane.org List-Id: linux-spi.vger.kernel.org On Mon, Mar 14, 2011 at 11:49:02AM -0400, Michael Williamson wrote: > The current davinci SPI driver, in DMA mode, is limited to 65535 > words for a single transfer. Modify the driver by configuring a > 3 dimensional EDMA transfer to support up to 65535x65535 > words. > > Signed-off-by: Michael Williamson > Tested-by: Stefano Babic Applied, thanks. > --- > changes since v0: > - Added spaces per style guide comments. > > This patch is an attempt to address the issue raised here: > > http://comments.gmane.org/gmane.linux.davinci/20581 > > Tested with: > dd if=/dev/mtd7 of=/tmp/test.1K bs=1024 count=1024 > dd if=/dev/mtd7 of=/tmp/test.64K bs=65536 count=16 > dd if=/dev/mtd7 of=/tmp/test.128K bs=131072 count=8 > md5sum /tmp/test* > > drivers/spi/davinci_spi.c | 33 +++++++++++++++++++++++++-------- > 1 files changed, 25 insertions(+), 8 deletions(-) > > diff --git a/drivers/spi/davinci_spi.c b/drivers/spi/davinci_spi.c > index 037ba82..1f0ed80 100644 > --- a/drivers/spi/davinci_spi.c > +++ b/drivers/spi/davinci_spi.c > @@ -571,6 +571,7 @@ static int davinci_spi_bufs(struct spi_device *spi, struct spi_transfer *t) > unsigned long tx_reg, rx_reg; > struct edmacc_param param; > void *rx_buf; > + int b, c; > > dma = &dspi->dma; > > @@ -599,14 +600,30 @@ static int davinci_spi_bufs(struct spi_device *spi, struct spi_transfer *t) > } > } > > + /* > + * If number of words is greater than 65535, then we need > + * to configure a 3 dimension transfer. Use the BCNTRLD > + * feature to allow for transfers that aren't even multiples > + * of 65535 (or any other possible b size) by first transferring > + * the remainder amount then grabbing the next N blocks of > + * 65535 words. > + */ > + > + c = dspi->wcount / (SZ_64K - 1); /* N 65535 Blocks */ > + b = dspi->wcount - c * (SZ_64K - 1); /* Remainder */ > + if (b) > + c++; > + else > + b = SZ_64K - 1; > + > param.opt = TCINTEN | EDMA_TCC(dma->tx_channel); > param.src = t->tx_buf ? t->tx_dma : tx_reg; > - param.a_b_cnt = dspi->wcount << 16 | data_type; > + param.a_b_cnt = b << 16 | data_type; > param.dst = tx_reg; > param.src_dst_bidx = t->tx_buf ? data_type : 0; > - param.link_bcntrld = 0xffff; > - param.src_dst_cidx = 0; > - param.ccnt = 1; > + param.link_bcntrld = 0xffffffff; > + param.src_dst_cidx = t->tx_buf ? data_type : 0; > + param.ccnt = c; > edma_write_slot(dma->tx_channel, ¶m); > edma_link(dma->tx_channel, dma->dummy_param_slot); > > @@ -643,12 +660,12 @@ static int davinci_spi_bufs(struct spi_device *spi, struct spi_transfer *t) > > param.opt = TCINTEN | EDMA_TCC(dma->rx_channel); > param.src = rx_reg; > - param.a_b_cnt = dspi->rcount << 16 | data_type; > + param.a_b_cnt = b << 16 | data_type; > param.dst = t->rx_dma; > param.src_dst_bidx = (t->rx_buf ? data_type : 0) << 16; > - param.link_bcntrld = 0xffff; > - param.src_dst_cidx = 0; > - param.ccnt = 1; > + param.link_bcntrld = 0xffffffff; > + param.src_dst_cidx = (t->rx_buf ? data_type : 0) << 16; > + param.ccnt = c; > edma_write_slot(dma->rx_channel, ¶m); > > if (pdata->cshold_bug) > -- > 1.7.0.4 >