From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nicolas Ferre Subject: Re: [PATCH 3/3] at_hdmac: add FIFO configuration parameter to DMA DT binding Date: Thu, 30 May 2013 18:32:16 +0200 Message-ID: <51A77F10.8020808@atmel.com> References: <1369930103-11963-1-git-send-email-ludovic.desroches@atmel.com> <1369930103-11963-4-git-send-email-ludovic.desroches@atmel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1369930103-11963-4-git-send-email-ludovic.desroches-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: devicetree-discuss-bounces+gldd-devicetree-discuss=m.gmane.org-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org Sender: "devicetree-discuss" To: ludovic.desroches-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org, vinod.koul-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org Cc: devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org On 30/05/2013 18:08, ludovic.desroches-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org : > From: Ludovic Desroches > > For most devices the FIFO configuration is the same i.e. when half FIFO size is > available/filled, a source/destination request is serviced. But USART devices > have to do it when there is enough space/data available to perform a single > AHB access so the ASAP configuration. > > Acked-by: Jean-Christophe PLAGNIOL-VILLARD > Signed-off-by: Ludovic Desroches Clear and neat: thanks Ludo. Acked-by: Nicolas Ferre > --- > .../devicetree/bindings/dma/atmel-dma.txt | 7 ++++-- > drivers/dma/at_hdmac.c | 25 ++++++++++++++++++---- > 2 files changed, 26 insertions(+), 6 deletions(-) > > diff --git a/Documentation/devicetree/bindings/dma/atmel-dma.txt b/Documentation/devicetree/bindings/dma/atmel-dma.txt > index c80e8a3..c280a0e 100644 > --- a/Documentation/devicetree/bindings/dma/atmel-dma.txt > +++ b/Documentation/devicetree/bindings/dma/atmel-dma.txt > @@ -24,8 +24,11 @@ The three cells in order are: > 1. A phandle pointing to the DMA controller. > 2. The memory interface (16 most significant bits), the peripheral interface > (16 less significant bits). > -3. The peripheral identifier for the hardware handshaking interface. The > -identifier can be different for tx and rx. > +3. Parameters for the at91 DMA configuration register which are device > +dependant: > + - bit 7-0: peripheral identifier for the hardware handshaking interface. The > + identifier can be different for tx and rx. > + - bit 11-8: FIFO configuration. 0 for half FIFO, 1 for ALAP, 1 for ASAP. > > Example: > > diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c > index e923cda..bfd73e1 100644 > --- a/drivers/dma/at_hdmac.c > +++ b/drivers/dma/at_hdmac.c > @@ -14,6 +14,7 @@ > * found on AT91SAM9263. > */ > > +#include > #include > #include > #include > @@ -1223,14 +1224,30 @@ static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec, > atslave = devm_kzalloc(&dmac_pdev->dev, sizeof(*atslave), GFP_KERNEL); > if (!atslave) > return NULL; > + > + atslave->cfg = ATC_DST_H2SEL_HW | ATC_SRC_H2SEL_HW; > /* > * We can fill both SRC_PER and DST_PER, one of these fields will be > * ignored depending on DMA transfer direction. > */ > - per_id = dma_spec->args[1]; > - atslave->cfg = ATC_FIFOCFG_HALFFIFO | ATC_DST_H2SEL_HW > - | ATC_SRC_H2SEL_HW | ATC_DST_PER(per_id) > - | ATC_SRC_PER(per_id); > + per_id = dma_spec->args[1] & AT91_DMA_CFG_PER_ID_MASK; > + atslave->cfg |= ATC_DST_PER(per_id) | ATC_SRC_PER(per_id); > + /* > + * We have to translate the value we get from the device tree since > + * the half FIFO configuration value had to be 0 to keep backward > + * compatibility. > + */ > + switch(dma_spec->args[1] & AT91_DMA_CFG_FIFOCFG_MASK) { > + case AT91_DMA_CFG_FIFOCFG_ALAP: > + atslave->cfg |= ATC_FIFOCFG_LARGESTBURST; > + break; > + case AT91_DMA_CFG_FIFOCFG_ASAP: > + atslave->cfg |= ATC_FIFOCFG_ENOUGHSPACE; > + break; > + case AT91_DMA_CFG_FIFOCFG_HALF: > + default: > + atslave->cfg |= ATC_FIFOCFG_HALFFIFO; > + } > atslave->dma_dev = &dmac_pdev->dev; > > chan = dma_request_channel(mask, at_dma_filter, atslave); > -- Nicolas Ferre