[PATCH v2 1/2] dma: pxa_dma: fix the no-requestor case

[PATCH v2 1/2] dma: pxa_dma: fix the no-requestor case

[Robert Jarzmik]

A very small number of devices don't use the flow control offered by
requestor lines. In these specific cases, the pxa dma driver should be
aware of that and not try to use a requestor line.

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
---
Since v1: rebase on v4.3-rc3
---
 drivers/dma/pxa_dma.c | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c
index 5cb61ce01036..7d3ff56caa0a 100644
--- a/drivers/dma/pxa_dma.c
+++ b/drivers/dma/pxa_dma.c
@@ -473,8 +473,10 @@ static void pxad_free_phy(struct pxad_chan *chan)
 		return;
 
 	/* clear the channel mapping in DRCMR */
-	reg = pxad_drcmr(chan->drcmr);
-	writel_relaxed(0, chan->phy->base + reg);
+	if (chan->drcmr <= DRCMR_CHLNUM) {
+		reg = pxad_drcmr(chan->drcmr);
+		writel_relaxed(0, chan->phy->base + reg);
+	}
 
 	spin_lock_irqsave(&pdev->phy_lock, flags);
 	for (i = 0; i < 32; i++)
@@ -516,8 +518,10 @@ static void phy_enable(struct pxad_phy *phy, bool misaligned)
 		"%s(); phy=%p(%d) misaligned=%d\n", __func__,
 		phy, phy->idx, misaligned);
 
-	reg = pxad_drcmr(phy->vchan->drcmr);
-	writel_relaxed(DRCMR_MAPVLD | phy->idx, phy->base + reg);
+	if (phy->vchan->drcmr <= DRCMR_CHLNUM) {
+		reg = pxad_drcmr(phy->vchan->drcmr);
+		writel_relaxed(DRCMR_MAPVLD | phy->idx, phy->base + reg);
+	}
 
 	dalgn = phy_readl_relaxed(phy, DALGN);
 	if (misaligned)
@@ -910,14 +914,18 @@ static void pxad_get_config(struct pxad_chan *chan,
 		width = chan->cfg.src_addr_width;
 		dev_addr = chan->cfg.src_addr;
 		*dev_src = dev_addr;
-		*dcmd |= PXA_DCMD_INCTRGADDR | PXA_DCMD_FLOWSRC;
+		*dcmd |= PXA_DCMD_INCTRGADDR;
+		if (chan->drcmr <= DRCMR_CHLNUM)
+			*dcmd |= PXA_DCMD_FLOWSRC;
 	}
 	if (dir == DMA_MEM_TO_DEV) {
 		maxburst = chan->cfg.dst_maxburst;
 		width = chan->cfg.dst_addr_width;
 		dev_addr = chan->cfg.dst_addr;
 		*dev_dst = dev_addr;
-		*dcmd |= PXA_DCMD_INCSRCADDR | PXA_DCMD_FLOWTRG;
+		*dcmd |= PXA_DCMD_INCSRCADDR;
+		if (chan->drcmr <= DRCMR_CHLNUM)
+			*dcmd |= PXA_DCMD_FLOWTRG;
 	}
 	if (dir == DMA_MEM_TO_MEM)
 		*dcmd |= PXA_DCMD_BURST32 | PXA_DCMD_INCTRGADDR |
-- 
2.1.4

[PATCH v2 2/2] dma: pxa_dma: fix residue corner case

[Robert Jarzmik]

A very tiny temporal window exists in the residue calculation where :
 - upon entering residue calculation, the transfer is ongoing
 - when reading the current transfer pointer, it just changed to
   the "finisher/linker" descriptor

In this case, the residue returned is the whole transfer length instead
of 0. Fix it.

This appears almost in one extreme case, where the driver is used
by older clients which inquire for residue in interrupt context, such
as the smsc91x ethernet driver, in a tight loop :
  interrupt_handler()
    dmaengine_submit()
    do {
      dmaengine_tx_status()
    } while (residue > 0 || status != DMA_ERROR)

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
---
Since v1: reworded the commit message for typos
---
 drivers/dma/pxa_dma.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c
index 7d3ff56caa0a..51f294e4227c 100644
--- a/drivers/dma/pxa_dma.c
+++ b/drivers/dma/pxa_dma.c
@@ -1185,6 +1185,16 @@ static unsigned int pxad_residue(struct pxad_chan *chan,
 	else
 		curr = phy_readl_relaxed(chan->phy, DTADR);
 
+	/*
+	 * curr has to be actually read before checking descriptor
+	 * completion, so that a curr inside a status updater
+	 * descriptor implies the following test returns true, and
+	 * preventing reordering of curr load and the test.
+	 */
+	rmb();
+	if (is_desc_completed(vd))
+		goto out;
+
 	for (i = 0; i < sw_desc->nb_desc - 1; i++) {
 		hw_desc = sw_desc->hw_desc[i];
 		if (sw_desc->hw_desc[0]->dcmd & PXA_DCMD_INCSRCADDR)
-- 
2.1.4

[PATCH v2 1/2] dma: pxa_dma: fix the no-requestor case

[Vinod Koul]

On Wed, Sep 30, 2015 at 07:42:14PM +0200, Robert Jarzmik wrote:
> A very small number of devices don't use the flow control offered by
> requestor lines. In these specific cases, the pxa dma driver should be
> aware of that and not try to use a requestor line.

Applied both now

Btw what happened to subsytem name here!!

-- 
~Vinod