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dmaengine: tegra-apb: Support non-flow controlled slave configuration

PATCH RESEND Applied Dmitry Osipenko 2 participants 2 messages Nov 16, 2017 – Nov 29, 2017 1 message not in the archive

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Dmitry Osipenko

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#0 lore raw

PATCH RESEND v2 1/1 dmaengine: tegra-apb: Support non-flow controlled slave configuration

This allows DMA client to issue a non-flow controlled TX. In particular it is needed for the fuse driver that reads fuse registers using APBDMA to workaround a HW bug that results in hang when CPU and DMA perform simultaneous access to fuse peripheral.

Signed-off-by Dmitry Osipenko <[email protected]>
Reviewed-by Jon Hunter <[email protected]>

---

Petch resent as per Vinod's request.

Change log:

v2:
- Removed trailing whitespace reported by checkpatch

 drivers/dma/tegra20-apb-dma.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)
drivers/dma/tegra20-apb-dma.c +14 -5
index b9d75a54c896..9a558e30c461 100644
@@ -353,7 +353,8 @@ static int tegra_dma_slave_config(struct dma_chan *dc,
 	}
 
 	memcpy(&tdc->dma_sconfig, sconfig, sizeof(*sconfig));
-	if (tdc->slave_id == TEGRA_APBDMA_SLAVE_ID_INVALID) {
+	if (tdc->slave_id == TEGRA_APBDMA_SLAVE_ID_INVALID &&
+	    sconfig->device_fc) {
 		if (sconfig->slave_id > TEGRA_APBDMA_CSR_REQ_SEL_MASK)
 			return -EINVAL;
 		tdc->slave_id = sconfig->slave_id;

@@ -970,8 +971,13 @@ static struct dma_async_tx_descriptor *tegra_dma_prep_slave_sg(
 					TEGRA_APBDMA_AHBSEQ_WRAP_SHIFT;
 	ahb_seq |= TEGRA_APBDMA_AHBSEQ_BUS_WIDTH_32;
 
-	csr |= TEGRA_APBDMA_CSR_ONCE | TEGRA_APBDMA_CSR_FLOW;
-	csr |= tdc->slave_id << TEGRA_APBDMA_CSR_REQ_SEL_SHIFT;
+	csr |= TEGRA_APBDMA_CSR_ONCE;
+
+	if (tdc->slave_id != TEGRA_APBDMA_SLAVE_ID_INVALID) {
+		csr |= TEGRA_APBDMA_CSR_FLOW;
+		csr |= tdc->slave_id << TEGRA_APBDMA_CSR_REQ_SEL_SHIFT;
+	}
+
 	if (flags & DMA_PREP_INTERRUPT)
 		csr |= TEGRA_APBDMA_CSR_IE_EOC;
 

@@ -1110,10 +1116,13 @@ static struct dma_async_tx_descriptor *tegra_dma_prep_dma_cyclic(
 					TEGRA_APBDMA_AHBSEQ_WRAP_SHIFT;
 	ahb_seq |= TEGRA_APBDMA_AHBSEQ_BUS_WIDTH_32;
 
-	csr |= TEGRA_APBDMA_CSR_FLOW;
+	if (tdc->slave_id != TEGRA_APBDMA_SLAVE_ID_INVALID) {
+		csr |= TEGRA_APBDMA_CSR_FLOW;
+		csr |= tdc->slave_id << TEGRA_APBDMA_CSR_REQ_SEL_SHIFT;
+	}
+
 	if (flags & DMA_PREP_INTERRUPT)
 		csr |= TEGRA_APBDMA_CSR_IE_EOC;
-	csr |= tdc->slave_id << TEGRA_APBDMA_CSR_REQ_SEL_SHIFT;
 
 	apb_seq |= TEGRA_APBDMA_APBSEQ_WRAP_WORD_1;
Signature · 1 line
2.14.2

A message that is not in the archive (sent off-list or not yet received): 20171116171106.25932-1-digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

Applied
#2 lore raw
Quoted 4 lines · Dmitry Osipenko

This allows DMA client to issue a non-flow controlled TX. In particular it is needed for the fuse driver that reads fuse registers using APBDMA to workaround a HW bug that results in hang when CPU and DMA perform simultaneous access to fuse peripheral.

Applied, thanks

Signature · 1 line
~Vinod