Re: [PATCH v2 0/6] OMAP2+ OneNAND driver update

[Ladislav Michl <ladis@linux-mips.org>]

On Wed, Nov 08, 2017 at 08:40:24AM +0100, Ladislav Michl wrote:
> Hi there,
> 
> this patch serie updates OMAP2+ OneNAND driver to the present times, making
> it fully DT configurable.
> 
> Patch 1 can be applied any time, it shows onenand node example and support
> for onenand is currently broken on igeps - hence this patches.

Now, looking more carefully at omap2 vs omap3 differences, following was
found:
- DMA code for both is basically the same
- OMAP2 DMA was disabled since very first commit
- second commit added gpio quirk.
- OMAP3 DMA code open coded waiting for completion timeout, but there's
  no dma stop if that happens. Does it even happened?
- At present time noone is using DMA nor GPIO.

That said, I'm temped to smash OMAP2 vs OMAP3 differences as that basically
means one more register read. Then we could kill newborn ti,omap3-onenand
compatible.

Objections? (and please do test driver if you have affected hardware,
thank you)

DMA unification looks like:

diff --git a/drivers/mtd/onenand/omap2.c b/drivers/mtd/onenand/omap2.c
index 883993bbe40b..5760e40be008 100644
--- a/drivers/mtd/onenand/omap2.c
+++ b/drivers/mtd/onenand/omap2.c
@@ -289,9 +289,7 @@ static inline int omap2_onenand_bufferram_offset(struct mtd_info *mtd, int area)
 	return 0;
 }
 
-#if defined(CONFIG_ARCH_OMAP3) || defined(MULTI_OMAP2)
-
-static int omap3_onenand_read_bufferram(struct mtd_info *mtd, int area,
+static int omap2_onenand_read_bufferram(struct mtd_info *mtd, int area,
 					unsigned char *buffer, int offset,
 					size_t count)
 {
@@ -299,10 +297,9 @@ static int omap3_onenand_read_bufferram(struct mtd_info *mtd, int area,
 	struct onenand_chip *this = mtd->priv;
 	dma_addr_t dma_src, dma_dst;
 	int bram_offset;
-	unsigned long timeout;
+	unsigned long t;
 	void *buf = (void *)buffer;
 	size_t xtra;
-	volatile unsigned *done;
 
 	bram_offset = omap2_onenand_bufferram_offset(mtd, area) + area + offset;
 	if (bram_offset & 3 || (size_t)buf & 3 || count < 384)
@@ -349,15 +346,11 @@ static int omap3_onenand_read_bufferram(struct mtd_info *mtd, int area,
 	reinit_completion(&c->dma_done);
 	omap_start_dma(c->dma_channel);
 
-	timeout = jiffies + msecs_to_jiffies(20);
-	done = &c->dma_done.done;
-	while (time_before(jiffies, timeout))
-		if (*done)
-			break;
+	t = wait_for_completion_io_timeout(&c->dma_done, msecs_to_jiffies(20));
 
 	dma_unmap_single(&c->pdev->dev, dma_dst, count, DMA_FROM_DEVICE);
 
-	if (!*done) {
+	if (!t) {
 		dev_err(&c->pdev->dev, "timeout waiting for DMA\n");
 		goto out_copy;
 	}
@@ -369,7 +362,7 @@ static int omap3_onenand_read_bufferram(struct mtd_info *mtd, int area,
 	return 0;
 }
 
-static int omap3_onenand_write_bufferram(struct mtd_info *mtd, int area,
+static int omap2_onenand_write_bufferram(struct mtd_info *mtd, int area,
 					 const unsigned char *buffer,
 					 int offset, size_t count)
 {
@@ -377,9 +370,8 @@ static int omap3_onenand_write_bufferram(struct mtd_info *mtd, int area,
 	struct onenand_chip *this = mtd->priv;
 	dma_addr_t dma_src, dma_dst;
 	int bram_offset;
-	unsigned long timeout;
+	unsigned long t;
 	void *buf = (void *)buffer;
-	volatile unsigned *done;
 
 	bram_offset = omap2_onenand_bufferram_offset(mtd, area) + area + offset;
 	if (bram_offset & 3 || (size_t)buf & 3 || count < 384)
@@ -420,15 +412,11 @@ static int omap3_onenand_write_bufferram(struct mtd_info *mtd, int area,
 	reinit_completion(&c->dma_done);
 	omap_start_dma(c->dma_channel);
 
-	timeout = jiffies + msecs_to_jiffies(20);
-	done = &c->dma_done.done;
-	while (time_before(jiffies, timeout))
-		if (*done)
-			break;
+	t = wait_for_completion_io_timeout(&c->dma_done, msecs_to_jiffies(20));
 
 	dma_unmap_single(&c->pdev->dev, dma_src, count, DMA_TO_DEVICE);
 
-	if (!*done) {
+	if (!t) {
 		dev_err(&c->pdev->dev, "timeout waiting for DMA\n");
 		goto out_copy;
 	}
@@ -440,134 +428,6 @@ static int omap3_onenand_write_bufferram(struct mtd_info *mtd, int area,
 	return 0;
 }
 
-#else
-
-static int omap3_onenand_read_bufferram(struct mtd_info *mtd, int area,
-					unsigned char *buffer, int offset,
-					size_t count)
-{
-	return -ENOSYS;
-}
-
-static int omap3_onenand_write_bufferram(struct mtd_info *mtd, int area,
-					 const unsigned char *buffer,
-					 int offset, size_t count)
-{
-	return -ENOSYS;
-}
-
-#endif
-
-#if defined(CONFIG_ARCH_OMAP2) || defined(MULTI_OMAP2)
-
-static int omap2_onenand_read_bufferram(struct mtd_info *mtd, int area,
-					unsigned char *buffer, int offset,
-					size_t count)
-{
-	struct omap2_onenand *c = container_of(mtd, struct omap2_onenand, mtd);
-	struct onenand_chip *this = mtd->priv;
-	dma_addr_t dma_src, dma_dst;
-	int bram_offset;
-
-	bram_offset = omap2_onenand_bufferram_offset(mtd, area) + area + offset;
-	/* DMA is not used.  Revisit PM requirements before enabling it. */
-	if (1 || (c->dma_channel < 0) ||
-	    ((void *) buffer >= (void *) high_memory) || (bram_offset & 3) ||
-	    (((unsigned int) buffer) & 3) || (count < 1024) || (count & 3)) {
-		memcpy(buffer, (__force void *)(this->base + bram_offset),
-		       count);
-		return 0;
-	}
-
-	dma_src = c->phys_base + bram_offset;
-	dma_dst = dma_map_single(&c->pdev->dev, buffer, count,
-				 DMA_FROM_DEVICE);
-	if (dma_mapping_error(&c->pdev->dev, dma_dst)) {
-		dev_err(&c->pdev->dev,
-			"Couldn't DMA map a %d byte buffer\n",
-			count);
-		return -1;
-	}
-
-	omap_set_dma_transfer_params(c->dma_channel, OMAP_DMA_DATA_TYPE_S32,
-				     count / 4, 1, 0, 0, 0);
-	omap_set_dma_src_params(c->dma_channel, 0, OMAP_DMA_AMODE_POST_INC,
-				dma_src, 0, 0);
-	omap_set_dma_dest_params(c->dma_channel, 0, OMAP_DMA_AMODE_POST_INC,
-				 dma_dst, 0, 0);
-
-	reinit_completion(&c->dma_done);
-	omap_start_dma(c->dma_channel);
-	wait_for_completion(&c->dma_done);
-
-	dma_unmap_single(&c->pdev->dev, dma_dst, count, DMA_FROM_DEVICE);
-
-	return 0;
-}
-
-static int omap2_onenand_write_bufferram(struct mtd_info *mtd, int area,
-					 const unsigned char *buffer,
-					 int offset, size_t count)
-{
-	struct omap2_onenand *c = container_of(mtd, struct omap2_onenand, mtd);
-	struct onenand_chip *this = mtd->priv;
-	dma_addr_t dma_src, dma_dst;
-	int bram_offset;
-
-	bram_offset = omap2_onenand_bufferram_offset(mtd, area) + area + offset;
-	/* DMA is not used.  Revisit PM requirements before enabling it. */
-	if (1 || (c->dma_channel < 0) ||
-	    ((void *) buffer >= (void *) high_memory) || (bram_offset & 3) ||
-	    (((unsigned int) buffer) & 3) || (count < 1024) || (count & 3)) {
-		memcpy((__force void *)(this->base + bram_offset), buffer,
-		       count);
-		return 0;
-	}
-
-	dma_src = dma_map_single(&c->pdev->dev, (void *) buffer, count,
-				 DMA_TO_DEVICE);
-	dma_dst = c->phys_base + bram_offset;
-	if (dma_mapping_error(&c->pdev->dev, dma_src)) {
-		dev_err(&c->pdev->dev,
-			"Couldn't DMA map a %d byte buffer\n",
-			count);
-		return -1;
-	}
-
-	omap_set_dma_transfer_params(c->dma_channel, OMAP_DMA_DATA_TYPE_S16,
-				     count / 2, 1, 0, 0, 0);
-	omap_set_dma_src_params(c->dma_channel, 0, OMAP_DMA_AMODE_POST_INC,
-				dma_src, 0, 0);
-	omap_set_dma_dest_params(c->dma_channel, 0, OMAP_DMA_AMODE_POST_INC,
-				 dma_dst, 0, 0);
-
-	reinit_completion(&c->dma_done);
-	omap_start_dma(c->dma_channel);
-	wait_for_completion(&c->dma_done);
-
-	dma_unmap_single(&c->pdev->dev, dma_src, count, DMA_TO_DEVICE);
-
-	return 0;
-}
-
-#else
-
-static int omap2_onenand_read_bufferram(struct mtd_info *mtd, int area,
-					unsigned char *buffer, int offset,
-					size_t count)
-{
-	return -ENOSYS;
-}
-
-static int omap2_onenand_write_bufferram(struct mtd_info *mtd, int area,
-					 const unsigned char *buffer,
-					 int offset, size_t count)
-{
-	return -ENOSYS;
-}
-
-#endif
-
 static struct platform_driver omap2_onenand_driver;
 
 static void omap2_onenand_shutdown(struct platform_device *pdev)
@@ -691,13 +551,8 @@ static int omap2_onenand_probe(struct platform_device *pdev)
 	this = &c->onenand;
 	if (c->dma_channel >= 0) {
 		this->wait = omap2_onenand_wait;
-		if (c->flags & ONENAND_IN_OMAP34XX) {
-			this->read_bufferram = omap3_onenand_read_bufferram;
-			this->write_bufferram = omap3_onenand_write_bufferram;
-		} else {
-			this->read_bufferram = omap2_onenand_read_bufferram;
-			this->write_bufferram = omap2_onenand_write_bufferram;
-		}
+		this->read_bufferram = omap2_onenand_read_bufferram;
+		this->write_bufferram = omap2_onenand_write_bufferram;
 	}
 
 	if ((r = onenand_scan(&c->mtd, 1)) < 0)
> Patches 3, 4 and 5 and intended for 4.15 merge window via mtd-tree as they
> are cleanups only.
> 
> Patches 2 and 6 are targetted for 4.16 merge window via mtd tree as it seems
> nobody tested these changes (on Nokias most importantly) so far.
> 
> Please note that unlike previous driver version, which basically ignored
> DT specified timings, this one relies on it, so it is important to get
> it right in your DT (dumping it from previous kernel version).
> 
> In case synchronous timings is requested, it is okay to specify timings
> for the slowest chip ever used for you board as it is evetually optimized
> after chip probe.
> 
>         ladis
> --
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