On 24-06-20, 10:35, André Przywara wrote:

On 24/06/2020 07:15, Vinod Koul wrote:

quoted

On 09-06-20, 15:47, Amit Singh Tomar wrote:

quoted

@@ -372,6 +383,7 @@ static inline int owl_dma_cfg_lli(struct owl_dma_vchan *vchan,
 				  struct dma_slave_config *sconfig,
 				  bool is_cyclic)
 {
+	struct owl_dma *od = to_owl_dma(vchan->vc.chan.device);
 	u32 mode, ctrlb;
 
 	mode = OWL_DMA_MODE_PW(0);

@@ -427,14 +439,26 @@ static inline int owl_dma_cfg_lli(struct owl_dma_vchan *vchan,
 	lli->hw[OWL_DMADESC_DADDR] = dst;
 	lli->hw[OWL_DMADESC_SRC_STRIDE] = 0;
 	lli->hw[OWL_DMADESC_DST_STRIDE] = 0;
-	/*
-	 * Word starts from offset 0xC is shared between frame length
-	 * (max frame length is 1MB) and frame count, where first 20
-	 * bits are for frame length and rest of 12 bits are for frame
-	 * count.
-	 */
-	lli->hw[OWL_DMADESC_FLEN] = len | FCNT_VAL << 20;
-	lli->hw[OWL_DMADESC_CTRLB] = ctrlb;
+
+	if (od->devid == S700_DMA) {
+		/* Max frame length is 1MB */
+		lli->hw[OWL_DMADESC_FLEN] = len;
+		/*
+		 * On S700, word starts from offset 0x1C is shared between
+		 * frame count and ctrlb, where first 12 bits are for frame
+		 * count and rest of 20 bits are for ctrlb.
+		 */
+		lli->hw[OWL_DMADESC_CTRLB] = FCNT_VAL | ctrlb;
+	} else {
+		/*
+		 * On S900, word starts from offset 0xC is shared between
+		 * frame length (max frame length is 1MB) and frame count,
+		 * where first 20 bits are for frame length and rest of
+		 * 12 bits are for frame count.
+		 */
+		lli->hw[OWL_DMADESC_FLEN] = len | FCNT_VAL << 20;
+		lli->hw[OWL_DMADESC_CTRLB] = ctrlb;

Unfortunately this wont scale, we will keep adding new conditions for
newer SoC's! So rather than this why not encode max frame length in
driver_data rather than S900_DMA/S700_DMA.. In future one can add values
for newer SoC and not code above logic again.

What newer SoCs? I don't think we should try to guess the future here.

In a patch for adding new SoC, quite ironical I would say!

We can always introduce further abstractions later, once we actually
*know* what we are looking at.

Rather if we know we are adding abstractions, why not add in a way that
makes it scale better rather than rework again

Besides, I don't understand what you are after. The max frame length is
1MB in both cases, it's just a matter of where to put FCNT_VAL, either
in FLEN or in CTRLB. And having an extra flag for that in driver data
sounds a bit over the top at the moment.

Maybe, maybe not. I would rather make it support N SoC when adding
support for second one rather than keep adding everytime a new SoC is
added...

-- 
~Vinod

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