[U-Boot] [linux-sunxi] Uboot error: address not aligned in v7_dcache_inval_range

[U-Boot] [linux-sunxi] Uboot error: address not aligned in v7_dcache_inval_range

[Ian Campbell]

On Sun, 2014-04-13 at 23:45 -0400, Shixin Zeng wrote:
> Hi,
> 
> I compiled the current u-boot from
> https://github.com/jwrdegoede/u-boot-sunxi.git for cubieboard2, and
> wrote it to the SD card. I was trying to boot the kernel on my
> computer over network by tftp, however it failed when I ran "dhcp" or
> "tftp" command in uboot with a tons of:
> 
> 
> ERROR: v7_dcache_inval_range - start address is not aligned - 0x7fb677e0
> ERROR: v7_dcache_inval_range - stop address is not aligned - 0x7fb67820

I'm seeing this on Cubieboard2 and Cubietruck. It appears to be down to
a change to the upstream designware driver:

commit 50b0df814b0f75c08a3d45a017016a75af3edb5d
Author: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
Date:   Wed Jan 22 20:49:09 2014 +0400

    net/designware: make driver compatible with data cache
    
    Up until now this driver only worked with data cache disabled.
    To make it work with enabled data cache following changes were required:
    
     * Flush Tx/Rx buffer descriptors their modification
     * Invalidate Tx/Rx buffer descriptors before reading its values
     * Flush cache for data passed from CPU to GMAC
     * Invalidate cache for data passed from GMAC to CPU

http://git.denx.de/?p=u-boot.git;a=commit;h=50b0df814b0f75c08a3d45a017016a75af3edb5d

I suppose this was only tested on some architecture which allows DMA
flush/invaidation at a fairly fine granularity (at least down to 4 byte
boundaries)
 
Making sure that struct dw_eth_dev is DMA aligned helps with the
invalidate of the descriptors in dw_eth_recv (see below) but with that
the invalidate of the txrx_status field in dw_eth_send is still
problematic -- the field is only 4 bytes, so although the descriptor is
aligned the end is not.

Ian.


commit 8878d858ede12584b885fa9439f9093bf2186a90
Author: Ian Campbell <ijc@hellion.org.uk>
Date:   Sat Apr 19 14:16:04 2014 +0100

    net/designware: ensure device private data is DMA aligned.
    
    struct dw_eth_dev contains fields which are accessed via DMA, so make sure it
    is aligned to a dma boundary. Without this I see:
        ERROR: v7_dcache_inval_range - start address is not aligned - 0x7fb677e0
    
    Signed-off-by: Ian Campbell <ian.campbell@citrix.com>

diff --git a/drivers/net/designware.c b/drivers/net/designware.c
index 6ece479..1120f70 100644
--- a/drivers/net/designware.c
+++ b/drivers/net/designware.c
@@ -412,7 +412,8 @@ int designware_initialize(ulong base_addr, u32 interface)
 	 * Since the priv structure contains the descriptors which need a strict
 	 * buswidth alignment, memalign is used to allocate memory
 	 */
-	priv = (struct dw_eth_dev *) memalign(16, sizeof(struct dw_eth_dev));
+	priv = (struct dw_eth_dev *) memalign(ARCH_DMA_MINALIGN,
+					      sizeof(struct dw_eth_dev));
 	if (!priv) {
 		free(dev);
 		return -ENOMEM;

[U-Boot] [PATCH 1/3] net/designware: ensure device private data is DMA aligned.

[Ian Campbell]

struct dw_eth_dev contains fields which are accessed via DMA, so make sure it
is aligned to a dma boundary. Without this I see:
    ERROR: v7_dcache_inval_range - start address is not aligned - 0x7fb677e0

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
---
 drivers/net/designware.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/designware.c b/drivers/net/designware.c
index 6ece479..1120f70 100644
--- a/drivers/net/designware.c
+++ b/drivers/net/designware.c
@@ -412,7 +412,8 @@ int designware_initialize(ulong base_addr, u32 interface)
 	 * Since the priv structure contains the descriptors which need a strict
 	 * buswidth alignment, memalign is used to allocate memory
 	 */
-	priv = (struct dw_eth_dev *) memalign(16, sizeof(struct dw_eth_dev));
+	priv = (struct dw_eth_dev *) memalign(ARCH_DMA_MINALIGN,
+					      sizeof(struct dw_eth_dev));
 	if (!priv) {
 		free(dev);
 		return -ENOMEM;
-- 
1.9.0

[U-Boot] [PATCH 1/3] net/designware: ensure device private data is DMA aligned.

[Alexey Brodkin]

Dear Ian,

On Sat, 2014-04-19 at 14:52 +0100, Ian Campbell wrote:
> struct dw_eth_dev contains fields which are accessed via DMA, so make sure it
> is aligned to a dma boundary. Without this I see:
>     ERROR: v7_dcache_inval_range - start address is not aligned - 0x7fb677e0
> 
> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> ---
>  drivers/net/designware.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/designware.c b/drivers/net/designware.c
> index 6ece479..1120f70 100644
> --- a/drivers/net/designware.c
> +++ b/drivers/net/designware.c
> @@ -412,7 +412,8 @@ int designware_initialize(ulong base_addr, u32 interface)
>  	 * Since the priv structure contains the descriptors which need a strict
>  	 * buswidth alignment, memalign is used to allocate memory
>  	 */
> -	priv = (struct dw_eth_dev *) memalign(16, sizeof(struct dw_eth_dev));
> +	priv = (struct dw_eth_dev *) memalign(ARCH_DMA_MINALIGN,
> +					      sizeof(struct dw_eth_dev));
>  	if (!priv) {
>  		free(dev);
>  		return -ENOMEM;

Thanks for this fix.
It was a left-over from initially submitted driver and I missed this
hard-coded item.

Still I haven't tried to execute this on the real board.
Hope to do it soon but I don't expect any issues.

Regards,
Alexey

Reviewed-by: Alexey Brodkin <abrodkin@synopsys.com>

[U-Boot] [PATCH 1/3] net/designware: ensure device private data is DMA aligned.

[Marek Vasut]

On Saturday, April 19, 2014 at 03:52:20 PM, Ian Campbell wrote:
> struct dw_eth_dev contains fields which are accessed via DMA, so make sure
> it is aligned to a dma boundary. Without this I see:
>     ERROR: v7_dcache_inval_range - start address is not aligned -
> 0x7fb677e0
> 
> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> ---
>  drivers/net/designware.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/designware.c b/drivers/net/designware.c
> index 6ece479..1120f70 100644
> --- a/drivers/net/designware.c
> +++ b/drivers/net/designware.c
> @@ -412,7 +412,8 @@ int designware_initialize(ulong base_addr, u32
> interface) * Since the priv structure contains the descriptors which need
> a strict * buswidth alignment, memalign is used to allocate memory
>  	 */
> -	priv = (struct dw_eth_dev *) memalign(16, sizeof(struct dw_eth_dev));
> +	priv = (struct dw_eth_dev *) memalign(ARCH_DMA_MINALIGN,
> +					      sizeof(struct dw_eth_dev));

Acked-by: Marek Vasut <marex@denx.de>

Best regards,
Marek Vasut

[U-Boot] [PATCH 2/3] net/designware: invalidate entire descriptor in dw_eth_send

[Ian Campbell]

Some platforms cannot invalidate the cache at four byte intervals, so
invalidate the entire descriptor.

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
---
 drivers/net/designware.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/designware.c b/drivers/net/designware.c
index 1120f70..7d14cec 100644
--- a/drivers/net/designware.c
+++ b/drivers/net/designware.c
@@ -280,10 +280,13 @@ static int dw_eth_send(struct eth_device *dev, void *packet, int length)
 	u32 desc_num = priv->tx_currdescnum;
 	struct dmamacdescr *desc_p = &priv->tx_mac_descrtable[desc_num];
 
-	/* Invalidate only "status" field for the following check */
-	invalidate_dcache_range((unsigned long)&desc_p->txrx_status,
-				(unsigned long)&desc_p->txrx_status +
-				sizeof(desc_p->txrx_status));
+	/* Strictly we only need to invalidate the "status" field for
+	 * the following check, but on some platforms we cannot
+	 * invalidate only 4 bytes, so invalidate the the whole thing
+	 * which is known to be DMA aligned. */
+	invalidate_dcache_range((unsigned long)desc_p,
+				(unsigned long)desc_p +
+				sizeof(struct dmamacdescr));
 
 	/* Check if the descriptor is owned by CPU */
 	if (desc_p->txrx_status & DESC_TXSTS_OWNBYDMA) {
-- 
1.9.0

[U-Boot] [linux-sunxi] Re: [PATCH 2/3] net/designware: invalidate entire descriptor in dw_eth_send

[Ian Campbell]

On Sat, 2014-04-19 at 10:14 -0400, Stefan Monnier wrote:
> > Some platforms cannot invalidate the cache at four byte intervals, so
> > invalidate the entire descriptor.
> 
> Wouldn't it be simpler to make invalidate_dcache_range round up to the
> nearest aligned boundaries?
> 
> Can there ever be situations where invalidating "too much" could be
> a problem?

Yes, if there was any data you cared about in the rounded up region
after the region you were actually trying to invalidate.

"invalidate" here means "throw away the content of the cache line
without writing back to ram", which is what you want if the content of
RAM is more up to date than the cache (because the device has DMAd to
it).

So invalidating more than was asked for would more than likely lead to
subtle errors.

Ian.

[U-Boot] [PATCH 2/3] net/designware: invalidate entire descriptor in dw_eth_send

[Alexey Brodkin]

Dear Ian,

On Sat, 2014-04-19 at 14:52 +0100, Ian Campbell wrote:
> -	/* Invalidate only "status" field for the following check */
> -	invalidate_dcache_range((unsigned long)&desc_p->txrx_status,
> -				(unsigned long)&desc_p->txrx_status +
> -				sizeof(desc_p->txrx_status));
> +	/* Strictly we only need to invalidate the "status" field for
> +	 * the following check, but on some platforms we cannot
> +	 * invalidate only 4 bytes, so invalidate the the whole thing
> +	 * which is known to be DMA aligned. */
> +	invalidate_dcache_range((unsigned long)desc_p,
> +				(unsigned long)desc_p +
> +				sizeof(struct dmamacdescr));
>  
>  	/* Check if the descriptor is owned by CPU */
>  	if (desc_p->txrx_status & DESC_TXSTS_OWNBYDMA) {

Unfortunately I cannot recall exactly why I wanted to invalidate only
"status" field.

Now looking at this code I may assume that I wanted to save some CPU
cycles. Because:

1. We don't care about all other fields except "status". GMAC only
changes "status" field when it resets "OWNED_BY_DMA" flag and all other
fields CPU writes but not reads while sending packets.

2. We may save quite a few CPU cycles if only invalidating minimum
amount of bytes (remember each read from external memory may cost 100s
of cycles).

So I would advise:

1. Don't invalidate "sizeof(struct dmamacdescr)" but only
"roundup(sizeof(desc_p->txrx_status), ARCH_DMA_MINALIGN))".

2. In the following lines implements rounding as well:
============
	/* Flush data to be sent */
	flush_dcache_range((unsigned long)desc_p->dmamac_addr,
			   (unsigned long)desc_p->dmamac_addr + length);
============

We may be sure "desc_p->dmamac_addr" is properly aligned, but length
could be not-aligned. So I'd replace "length" with "roundup(length,
ARCH_DMA_MINALIGN)" as you did in 3rd patch.

3. Check carefully if there're other instances of probably unaligned
cache operations. I erroneously didn't care about alignment on cache
invalidation/flushing because my implementation of those cache
operations deals with non-aligned start/end internally within
invalidate/flush functions - which might be not that good even if it's
convenient for me.

4. Why don't you squeeze all 3 patches in 1 and name it like "fix
alignment issues with caches on some platforms"? Basically with all 3
patches you fix one and only issue and application of any one of those 3
patches doesn't solve your problem, right?

Regards,
Alexey

[U-Boot] [PATCH 2/3] net/designware: invalidate entire descriptor in dw_eth_send

[Ian Campbell]

On Thu, 2014-04-24 at 17:41 +0000, Alexey Brodkin wrote:

> 1. Don't invalidate "sizeof(struct dmamacdescr)" but only
> "roundup(sizeof(desc_p->txrx_status), ARCH_DMA_MINALIGN))".

OK. (Although given the realities of the real world values of
ARCH_DMA_MINALIGN on every arch and the sizes of the structs & fields
involved this isn't actually buying you anything at all)

> 2. In the following lines implements rounding as well:

Will fix as well.

> 3. Check carefully if there're other instances of probably unaligned
> cache operations.

I'm not seeing any others, in practice or by eye-balling the code.

> 4. Why don't you squeeze all 3 patches in 1 and name it like "fix
> alignment issues with caches on some platforms"? Basically with all 3
> patches you fix one and only issue and application of any one of those 3
> patches doesn't solve your problem, right?

These are the issues as I discovered them one by one. I can fold them if
you like but doing them separately will aid bisection if one of them
turns out to be wrong in some way. As you prefer.

Ian.

[U-Boot] [PATCH 2/3] net/designware: invalidate entire descriptor in dw_eth_send

[Alexey Brodkin]

Hi Ian,

On Thu, 2014-04-24 at 20:14 +0100, Ian Campbell wrote:
> On Thu, 2014-04-24 at 17:41 +0000, Alexey Brodkin wrote:
> 
> > 1. Don't invalidate "sizeof(struct dmamacdescr)" but only
> > "roundup(sizeof(desc_p->txrx_status), ARCH_DMA_MINALIGN))".
> 
> OK. (Although given the realities of the real world values of
> ARCH_DMA_MINALIGN on every arch and the sizes of the structs & fields
> involved this isn't actually buying you anything at all)

Well this particular structure is of size sizeof(uint32_t) * 4 = 16
bytes. And I may suppose that cache lines could be shorter than 16 bytes
even though it could be pretty rare situation. So definitely not a big
deal.

But since we're dealing with macros here all mentioned calculations will
be done by pre-processor and execution performance won't be affected.

> > 2. In the following lines implements rounding as well:
> 
> Will fix as well.
> 
> > 3. Check carefully if there're other instances of probably unaligned
> > cache operations.

I thought a bit more about this situation and now I'm not that sure if
we need to align addresses we pass to cache invalidate/flush functions.

Because IMHO drivers shouldn't care about specifics of particular
platform or architecture. Otherwise we'll need to patch each and every
driver only for cache invalidate/flush functions. I looked how these
functions are used in other drivers and see that in most of cases no
additional alignment precautions were implemented. People just pass
start and end addresses.

In its turn platform and architecture provides cache invalidate/flush
functions implement its functionality depending on hardware specifics.

For example on architectures that may only flush/invalidate with
granularity of 1 cache line cache invalidate/flush functions make sure
to start processing from the start of the cache line to which start
address falls and end processing when cache line where end address falls
is processed.

I may assume that there're architectures that automatically understand
from which cache line to start and at which line to stop processing.

But if your architecture requires cache line aligned addresses to be
used for start/end addresses you may look for examples in ARC
(http://git.denx.de/?p=u-boot/u-boot-arc.git;a=blob;f=arch/arc/cpu/arc700/cache.c),, MIPS (http://git.denx.de/?p=u-boot/u-boot-arc.git;a=blob;f=arch/mips/cpu/mips32/cpu.c), SH (http://git.denx.de/?p=u-boot/u-boot-arc.git;a=blob;f=arch/sh/cpu/sh4/cache.c),

and what's interesting even implementation you use have semi-proper
start/end addresses handling -
http://git.denx.de/?p=u-boot.git;a=blob;f=arch/arm/lib/cache-pl310.c

Here's your invalidation procedure:
============
/* invalidate memory from start to stop-1 */
void v7_outer_cache_inval_range(u32 start, u32 stop)
{
	/* PL310 currently supports only 32 bytes cache line */
	u32 pa, line_size = 32;

	/*
	 * If start address is not aligned to cache-line do not
	 * invalidate the first cache-line
	 */
	if (start & (line_size - 1)) {
		printf("ERROR: %s - start address is not aligned - 0x%08x\n",
			__func__, start);
		/* move to next cache line */
		start = (start + line_size - 1) & ~(line_size - 1);
	}

	/*
	 * If stop address is not aligned to cache-line do not
	 * invalidate the last cache-line
	 */
	if (stop & (line_size - 1)) {
		printf("ERROR: %s - stop address is not aligned - 0x%08x\n",
			__func__, stop);
		/* align to the beginning of this cache line */
		stop &= ~(line_size - 1);
	}

	for (pa = start; pa < stop; pa = pa + line_size)
		writel(pa, &pl310->pl310_inv_line_pa);

	pl310_cache_sync();
}
============

1. I don't understand why start from the next cache line if start
address is not aligned to cache line boundary? I'd say that you want to
invalidate cache line that contains unaligned start address. Otherwise
first bytes won't be invalidated, right?

2. Why do we throw _error_ message. I may understand if you emit
_warning_ message in case of debug build (with DEBUG defined). Well in
current implementation (see 1) it could be error because behavior is
really dangerous. But if you start from correct cache line only warning
in debug mode makes sense (IMHO).

3. Stop/end address in contrast might need to be extended depending on
HW implementation (see above comment).

And here's your flush procedure:
===========
void v7_outer_cache_flush_range(u32 start, u32 stop)
{
	/* PL310 currently supports only 32 bytes cache line */
	u32 pa, line_size = 32;

	/*
	 * Align to the beginning of cache-line - this ensures that
	 * the first 5 bits are 0 as required by PL310 TRM
	 */
	start &= ~(line_size - 1);

	for (pa = start; pa < stop; pa = pa + line_size)
		writel(pa, &pl310->pl310_clean_inv_line_pa);

	pl310_cache_sync();
}
===========

Which looks very correct to me. I'm wondering if there was a reason to
have so different implementation of functions that do very similar
things.

So at this point I would ask you to modify cache invalidate function for
your architecture. This way you prevent mentioned issues with other
drivers.

> I'm not seeing any others, in practice or by eye-balling the code.
> 
> > 4. Why don't you squeeze all 3 patches in 1 and name it like "fix
> > alignment issues with caches on some platforms"? Basically with all 3
> > patches you fix one and only issue and application of any one of those 3
> > patches doesn't solve your problem, right?
> 
> These are the issues as I discovered them one by one. I can fold them if
> you like but doing them separately will aid bisection if one of them
> turns out to be wrong in some way. As you prefer.

Keeping in mind things written above I'd say that patches 2 & 3 are not
needed at all, while patch 1 makes perfect sense and fixes an obvious
issue.

Regards,
Alexey

[U-Boot] [PATCH 2/3] net/designware: invalidate entire descriptor in dw_eth_send

[Ian Campbell]

CCing the ARM custodian. Albert, what do you think of Alexey's comments
below? Actually, having read it properly myself I think Alexey is
confusing cache flushing with cache invalidation, I've left the CC in
place though in case you have any thoughts on the matter.

On Fri, 2014-04-25 at 08:48 +0000, Alexey Brodkin wrote:
> I thought a bit more about this situation and now I'm not that sure if
> we need to align addresses we pass to cache invalidate/flush functions.
> 
> Because IMHO drivers shouldn't care about specifics of particular
> platform or architecture. Otherwise we'll need to patch each and every
> driver only for cache invalidate/flush functions. I looked how these
> functions are used in other drivers and see that in most of cases no
> additional alignment precautions were implemented. People just pass
> start and end addresses.
> 
> In its turn platform and architecture provides cache invalidate/flush
> functions implement its functionality depending on hardware specifics.
> 
> For example on architectures that may only flush/invalidate with
> granularity of 1 cache line cache invalidate/flush functions make sure
> to start processing from the start of the cache line to which start
> address falls and end processing when cache line where end address falls
> is processed.
> 
> I may assume that there're architectures that automatically understand
> from which cache line to start and at which line to stop processing.
> 
> But if your architecture requires cache line aligned addresses to be
> used for start/end addresses you may look for examples in ARC
> (http://git.denx.de/?p=u-boot/u-boot-arc.git;a=blob;f=arch/arc/cpu/arc700/cache.c),, MIPS (http://git.denx.de/?p=u-boot/u-boot-arc.git;a=blob;f=arch/mips/cpu/mips32/cpu.c), SH (http://git.denx.de/?p=u-boot/u-boot-arc.git;a=blob;f=arch/sh/cpu/sh4/cache.c),
> 
> and what's interesting even implementation you use have semi-proper
> start/end addresses handling -
> http://git.denx.de/?p=u-boot.git;a=blob;f=arch/arm/lib/cache-pl310.c

This is the driver for one particular ARM cache controller and not the
one used for the SoC. In any case it does "proper" start/end handling
only for cache flush operations, not cache invalidate.

Cache invalidate is a potentially destructive operation (throwing away
data in the caches), having it operate on anything more than the precise
region requested would be very surprising to almost anyone I think.

> 
> Here's your invalidation procedure:
> ============
> /* invalidate memory from start to stop-1 */
> void v7_outer_cache_inval_range(u32 start, u32 stop)
> {
> 	/* PL310 currently supports only 32 bytes cache line */
> 	u32 pa, line_size = 32;
> 
> 	/*
> 	 * If start address is not aligned to cache-line do not
> 	 * invalidate the first cache-line
> 	 */
> 	if (start & (line_size - 1)) {
> 		printf("ERROR: %s - start address is not aligned - 0x%08x\n",
> 			__func__, start);
> 		/* move to next cache line */
> 		start = (start + line_size - 1) & ~(line_size - 1);
> 	}
> 
> 	/*
> 	 * If stop address is not aligned to cache-line do not
> 	 * invalidate the last cache-line
> 	 */
> 	if (stop & (line_size - 1)) {
> 		printf("ERROR: %s - stop address is not aligned - 0x%08x\n",
> 			__func__, stop);
> 		/* align to the beginning of this cache line */
> 		stop &= ~(line_size - 1);
> 	}
> 
> 	for (pa = start; pa < stop; pa = pa + line_size)
> 		writel(pa, &pl310->pl310_inv_line_pa);
> 
> 	pl310_cache_sync();
> }
> ============
> 
> 1. I don't understand why start from the next cache line if start
> address is not aligned to cache line boundary? I'd say that you want to
> invalidate cache line that contains unaligned start address. Otherwise
> first bytes won't be invalidated, right?
> 
> 2. Why do we throw _error_ message. I may understand if you emit
> _warning_ message in case of debug build (with DEBUG defined). Well in
> current implementation (see 1) it could be error because behavior is
> really dangerous. But if you start from correct cache line only warning
> in debug mode makes sense (IMHO).
> 
> 3. Stop/end address in contrast might need to be extended depending on
> HW implementation (see above comment).
> 
> And here's your flush procedure:
> ===========
> void v7_outer_cache_flush_range(u32 start, u32 stop)
> {
> 	/* PL310 currently supports only 32 bytes cache line */
> 	u32 pa, line_size = 32;
> 
> 	/*
> 	 * Align to the beginning of cache-line - this ensures that
> 	 * the first 5 bits are 0 as required by PL310 TRM
> 	 */
> 	start &= ~(line_size - 1);
> 
> 	for (pa = start; pa < stop; pa = pa + line_size)
> 		writel(pa, &pl310->pl310_clean_inv_line_pa);
> 
> 	pl310_cache_sync();
> }
> ===========
> 
> Which looks very correct to me. I'm wondering if there was a reason to
> have so different implementation of functions that do very similar
> things.

I think you are missing the important differences between a cache flush
and a cache invalidate.

> So at this point I would ask you to modify cache invalidate function for
> your architecture. This way you prevent mentioned issues with other
> drivers.

As I describe above, I don't think this would be at all wise.

> > I'm not seeing any others, in practice or by eye-balling the code.
> > 
> > > 4. Why don't you squeeze all 3 patches in 1 and name it like "fix
> > > alignment issues with caches on some platforms"? Basically with all 3
> > > patches you fix one and only issue and application of any one of those 3
> > > patches doesn't solve your problem, right?
> > 
> > These are the issues as I discovered them one by one. I can fold them if
> > you like but doing them separately will aid bisection if one of them
> > turns out to be wrong in some way. As you prefer.
> 
> Keeping in mind things written above I'd say that patches 2 & 3 are not
> needed at all, while patch 1 makes perfect sense and fixes an obvious
> issue.
> 
> Regards,
> Alexey
> 

[U-Boot] [PATCH 2/3] net/designware: invalidate entire descriptor in dw_eth_send

[Alexey Brodkin]

Dear Ian,

On Sun, 2014-04-27 at 19:47 +0100, Ian Campbell wrote:

> This is the driver for one particular ARM cache controller and not the
> one used for the SoC. In any case it does "proper" start/end handling
> only for cache flush operations, not cache invalidate.
> 
> Cache invalidate is a potentially destructive operation (throwing away
> data in the caches), having it operate on anything more than the precise
> region requested would be very surprising to almost anyone I think.
...
> I think you are missing the important differences between a cache 
> flush and a cache invalidate.

IMHO cache invalidation and flush operations are sort of antipodes.

With invalidation you discard all data in corresponding line in cache
and replace it with freshly read data from memory.

With flush you move cache line to corresponding memory location
overriding previously existing values in memory.

So if you deal with 2 independent data fields which both share the same
one cache line it's potentially dangerous to do both flush and
invalidate of this cache line.

In case of MMU utilization we have a luxury of uncached access, so we
may safely access control structures in memory with granularity which is
available for this particular CPU. This is AFAIK drivers deal with
buffer descriptors in Linux kernel.

In case of U-Boot where we prefer to keep things simple we don't use
MMU. So no generic way for cache bypassing. Still some architectures
like ARC700 have special instructions for accessing memory bypassing
cache but I prever to not use them and keep sources
platform-independent.

And in this situation IMHO the only safe solution could be in proper
design of data layout. In other words we need to keep independent data
blocks aligned to cache line.

And as you may see from "designware.h" buffer descriptor structure is
aligned:
==============
struct dmamacdescr {
	u32 txrx_status;
	u32 dmamac_cntl;
	void *dmamac_addr;
	struct dmamacdescr *dmamac_next;
} __aligned(ARCH_DMA_MINALIGN);
==============

Regards,
Alexey

[U-Boot] [PATCH 2/3] net/designware: invalidate entire descriptor in dw_eth_send

[Ian Campbell]

On Mon, 2014-04-28 at 12:05 +0000, Alexey Brodkin wrote:

> And in this situation IMHO the only safe solution could be in proper
> design of data layout. In other words we need to keep independent data
> blocks aligned to cache line.
> 
> And as you may see from "designware.h" buffer descriptor structure is
> aligned:

There's no point in taking all this care if you then go and flush
subfields, as the driver does, since they are not necessarily going to
have the required alignment. That was the entire point of this patch!

I'm going to do the roundup thing you asked for, even though it seems
like a pointless optimisation to me given the context.

> ==============
> struct dmamacdescr {
> 	u32 txrx_status;
> 	u32 dmamac_cntl;
> 	void *dmamac_addr;
> 	struct dmamacdescr *dmamac_next;
> } __aligned(ARCH_DMA_MINALIGN);
> ==============
> 
> Regards,
> Alexey
> 
> 
> 

[U-Boot] [PATCH 2/3] net/designware: invalidate entire descriptor in dw_eth_send

[Stefan Monnier]

> 1. Don't invalidate "sizeof(struct dmamacdescr)" but only
> "roundup(sizeof(desc_p->txrx_status), ARCH_DMA_MINALIGN))".

I'm not sure I like this: if ARCH_DMA_MINALIGN is "too large" and ends
up invalidating more than the struct, it could be an error, so it's
safer to ask it to invalidate the struct (which we know can be safely
invalidates).

If invalidate_dcache_range is used "often", then I'd suggest to change
its API so it receives 2 bounds: the one that has to be invalidated
and the surrounding one that can safely be invalidated.


        Stefan

[U-Boot] [PATCH 3/3] net/designware: align cache invalidation on rx

[Ian Campbell]

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
---
 drivers/net/designware.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/designware.c b/drivers/net/designware.c
index 7d14cec..30446d3 100644
--- a/drivers/net/designware.c
+++ b/drivers/net/designware.c
@@ -354,7 +354,7 @@ static int dw_eth_recv(struct eth_device *dev)
 		/* Invalidate received data */
 		invalidate_dcache_range((unsigned long)desc_p->dmamac_addr,
 					(unsigned long)desc_p->dmamac_addr +
-					length);
+					roundup(length, ARCH_DMA_MINALIGN));
 
 		NetReceive(desc_p->dmamac_addr, length);
 
-- 
1.9.0

[U-Boot] [linux-sunxi] [PATCH 3/3] net/designware: align cache invalidation on rx

[Shixin Zeng]

?
On Sat, Apr 19, 2014 at 9:52 AM, Ian Campbell <ijc@hellion.org.uk> wrote:

> Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
> ---
>  drivers/net/designware.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/net/designware.c b/drivers/net/designware.c
> index 7d14cec..30446d3 100644
> --- a/drivers/net/designware.c
> +++ b/drivers/net/designware.c
> @@ -354,7 +354,7 @@ static int dw_eth_recv(struct eth_device *dev)
>                 /* Invalidate received data */
>                 invalidate_dcache_range((unsigned long)desc_p->dmamac_addr,
>                                         (unsigned long)desc_p->dmamac_addr
> +
> -                                       length);
> +                                       roundup(length,
> ARCH_DMA_MINALIGN));
>
>                 NetReceive(desc_p->dmamac_addr, length);
>
> ?With these three patches, I don't see ?
v7_dcache_inval_range
?errors ?
anymore
?. Thanks!?
?

> --
> 1.9.0
>
> --
> You received this message because you are subscribed to the Google Groups
> "linux-sunxi" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to linux-sunxi+unsubscribe at googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.
>

[U-Boot] [linux-sunxi] Uboot error: address not aligned in v7_dcache_inval_range

[Shixin Zeng]

On Sat, Apr 19, 2014 at 9:30 AM, Ian Campbell <ijc@hellion.org.uk> wrote:

> On Sun, 2014-04-13 at 23:45 -0400, Shixin Zeng wrote:
> > Hi,
> >
> > I compiled the current u-boot from
> > https://github.com/jwrdegoede/u-boot-sunxi.git for cubieboard2, and
> > wrote it to the SD card. I was trying to boot the kernel on my
> > computer over network by tftp, however it failed when I ran "dhcp" or
> > "tftp" command in uboot with a tons of:
> >
> >
> > ERROR: v7_dcache_inval_range - start address is not aligned - 0x7fb677e0
> > ERROR: v7_dcache_inval_range - stop address is not aligned - 0x7fb67820
>
> I'm seeing this on Cubieboard2 and Cubietruck. It appears to be down to
> a change to the upstream designware driver:
>
> commit 50b0df814b0f75c08a3d45a017016a75af3edb5d
> Author: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
> Date:   Wed Jan 22 20:49:09 2014 +0400
>
>     net/designware: make driver compatible with data cache
>
>     Up until now this driver only worked with data cache disabled.
>     To make it work with enabled data cache following changes were
> required:
>
>      * Flush Tx/Rx buffer descriptors their modification
>      * Invalidate Tx/Rx buffer descriptors before reading its values
>      * Flush cache for data passed from CPU to GMAC
>      * Invalidate cache for data passed from GMAC to CPU
>
>
> http://git.denx.de/?p=u-boot.git;a=commit;h=50b0df814b0f75c08a3d45a017016a75af3edb5d
>
> I suppose this was only tested on some architecture which allows DMA
> flush/invaidation at a fairly fine granularity (at least down to 4 byte
> boundaries)
>
> Making sure that struct dw_eth_dev is DMA aligned helps with the
> invalidate of the descriptors in dw_eth_recv (see below) but with that
> the invalidate of the txrx_status field in dw_eth_send is still
> problematic -- the field is only 4 bytes, so although the descriptor is
> aligned the end is not.
>
> ?
Indeed, with this change, I now get these errors instead:

?

Loading: ERROR: v7_dcache_inval_range - stop address is not aligned -
0x7fb663c4
ERROR: v7_dcache_inval_range - stop address is not aligned - 0x7fb66404
ERROR: v7_dcache_inval_range - stop address is not aligned - 0x7fb6f401

Best Regards

Shixin Zeng
?

> Ian.
>
>
> commit 8878d858ede12584b885fa9439f9093bf2186a90
> Author: Ian Campbell <ijc@hellion.org.uk>
> Date:   Sat Apr 19 14:16:04 2014 +0100
>
>     net/designware: ensure device private data is DMA aligned.
>
>     struct dw_eth_dev contains fields which are accessed via DMA, so make
> sure it
>     is aligned to a dma boundary. Without this I see:
>         ERROR: v7_dcache_inval_range - start address is not aligned -
> 0x7fb677e0
>
>     Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
>
> diff --git a/drivers/net/designware.c b/drivers/net/designware.c
> index 6ece479..1120f70 100644
> --- a/drivers/net/designware.c
> +++ b/drivers/net/designware.c
> @@ -412,7 +412,8 @@ int designware_initialize(ulong base_addr, u32
> interface)
>          * Since the priv structure contains the descriptors which need a
> strict
>          * buswidth alignment, memalign is used to allocate memory
>          */
> -       priv = (struct dw_eth_dev *) memalign(16, sizeof(struct
> dw_eth_dev));
> +       priv = (struct dw_eth_dev *) memalign(ARCH_DMA_MINALIGN,
> +                                             sizeof(struct dw_eth_dev));
>         if (!priv) {
>                 free(dev);
>                 return -ENOMEM;
>
>
> --
> You received this message because you are subscribed to the Google Groups
> "linux-sunxi" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to linux-sunxi+unsubscribe at googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.
>

[U-Boot] [linux-sunxi] Uboot error: address not aligned in v7_dcache_inval_range

[Marek Vasut]

On Saturday, April 19, 2014 at 03:30:14 PM, Ian Campbell wrote:
> On Sun, 2014-04-13 at 23:45 -0400, Shixin Zeng wrote:
> > Hi,
> > 
> > I compiled the current u-boot from
> > https://github.com/jwrdegoede/u-boot-sunxi.git for cubieboard2, and
> > wrote it to the SD card. I was trying to boot the kernel on my
> > computer over network by tftp, however it failed when I ran "dhcp" or
> > "tftp" command in uboot with a tons of:
> > 
> > 
> > ERROR: v7_dcache_inval_range - start address is not aligned - 0x7fb677e0
> > ERROR: v7_dcache_inval_range - stop address is not aligned - 0x7fb67820
> 
> I'm seeing this on Cubieboard2 and Cubietruck. It appears to be down to
> a change to the upstream designware driver:
> 
> commit 50b0df814b0f75c08a3d45a017016a75af3edb5d
> Author: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
> Date:   Wed Jan 22 20:49:09 2014 +0400
> 
>     net/designware: make driver compatible with data cache
> 
>     Up until now this driver only worked with data cache disabled.
>     To make it work with enabled data cache following changes were
> required:
> 
>      * Flush Tx/Rx buffer descriptors their modification
>      * Invalidate Tx/Rx buffer descriptors before reading its values
>      * Flush cache for data passed from CPU to GMAC
>      * Invalidate cache for data passed from GMAC to CPU
> 
> http://git.denx.de/?p=u-boot.git;a=commit;h=50b0df814b0f75c08a3d45a017016a7
> 5af3edb5d
> 
> I suppose this was only tested on some architecture which allows DMA
> flush/invaidation at a fairly fine granularity (at least down to 4 byte
> boundaries)

This was a sheer luck this ever worked. Looking at the entire driver, to fix all 
your issues with DMA and caches, it would be sufficient to re-align "struct 
dw_eth_dev" properly.

See drivers/net/designware.h:
1) struct dmamacdescr {} is already __aligned(ARCH_DMA_MINALIGN)
   => This structure, if aligned in memory to proper boundary, can be flushed/
      invalidated without problems.
2) struct dw_eth_dev {} can be aligned to ANY 4-byte boundary
   But this structure contains two arrays of struct dmamacdescr {} , which each
   have their elements' lenght aligned to ARCH_DMA_MINALIGN

Solution:

Your patch [1/3] and reorder the structure in designware.h so that the
struct dmamacdescr tx_mac_descrtable[]
struct dmamacdescr rx_mac_descrtable[]
are first and anything that does not need to be aligned follows. This way, the 
DMA descriptors will always be aligned and you need not worry about the flushes. 
You don't even need to ROUNDUP their length, since they are already fine.

When reordering the struct dw_eth_dev {}, make sure to add a comment about the 
alignment.

Best regards,
Marek Vasut

[U-Boot] [linux-sunxi] Uboot error: address not aligned in v7_dcache_inval_range

[Ian Campbell]

On Sat, 2014-04-26 at 20:27 +0200, Marek Vasut wrote:

> This was a sheer luck this ever worked. Looking at the entire driver, to fix all 
> your issues with DMA and caches, it would be sufficient to re-align "struct 
> dw_eth_dev" properly.
> 
> See drivers/net/designware.h:
> 1) struct dmamacdescr {} is already __aligned(ARCH_DMA_MINALIGN)
>    => This structure, if aligned in memory to proper boundary, can be flushed/
>       invalidated without problems.
> 2) struct dw_eth_dev {} can be aligned to ANY 4-byte boundary
>    But this structure contains two arrays of struct dmamacdescr {} , which each
>    have their elements' lenght aligned to ARCH_DMA_MINALIGN
> 
> Solution:
> 
> Your patch [1/3] and reorder the structure in designware.h so that the
> struct dmamacdescr tx_mac_descrtable[]
> struct dmamacdescr rx_mac_descrtable[]
> are first and anything that does not need to be aligned follows. This way, the 
> DMA descriptors will always be aligned and you need not worry about the flushes. 
> You don't even need to ROUNDUP their length, since they are already fine.

That sounds like a good plan. I'll take a look.

> When reordering the struct dw_eth_dev {}, make sure to add a comment about the 
> alignment.

Of course.

Ian.

[U-Boot] [linux-sunxi] Uboot error: address not aligned in v7_dcache_inval_range

[Marek Vasut]

On Sunday, April 27, 2014 at 08:40:50 PM, Ian Campbell wrote:
> On Sat, 2014-04-26 at 20:27 +0200, Marek Vasut wrote:
> > This was a sheer luck this ever worked. Looking at the entire driver, to
> > fix all your issues with DMA and caches, it would be sufficient to
> > re-align "struct dw_eth_dev" properly.
> > 
> > See drivers/net/designware.h:
> > 1) struct dmamacdescr {} is already __aligned(ARCH_DMA_MINALIGN)
> > 
> >    => This structure, if aligned in memory to proper boundary, can be
> >    flushed/
> >    
> >       invalidated without problems.
> > 
> > 2) struct dw_eth_dev {} can be aligned to ANY 4-byte boundary
> > 
> >    But this structure contains two arrays of struct dmamacdescr {} ,
> >    which each have their elements' lenght aligned to ARCH_DMA_MINALIGN
> > 
> > Solution:
> > 
> > Your patch [1/3] and reorder the structure in designware.h so that the
> > struct dmamacdescr tx_mac_descrtable[]
> > struct dmamacdescr rx_mac_descrtable[]
> > are first and anything that does not need to be aligned follows. This
> > way, the DMA descriptors will always be aligned and you need not worry
> > about the flushes. You don't even need to ROUNDUP their length, since
> > they are already fine.
> 
> That sounds like a good plan. I'll take a look.
> 
> > When reordering the struct dw_eth_dev {}, make sure to add a comment
> > about the alignment.
> 
> Of course.

Thanks

Best regards,
Marek Vasut

[U-Boot] [linux-sunxi] Uboot error: address not aligned in v7_dcache_inval_range

[Ian Campbell]

On Sat, 2014-04-26 at 20:27 +0200, Marek Vasut wrote:
> On Saturday, April 19, 2014 at 03:30:14 PM, Ian Campbell wrote:
> > On Sun, 2014-04-13 at 23:45 -0400, Shixin Zeng wrote:
> > > Hi,
> > > 
> > > I compiled the current u-boot from
> > > https://github.com/jwrdegoede/u-boot-sunxi.git for cubieboard2, and
> > > wrote it to the SD card. I was trying to boot the kernel on my
> > > computer over network by tftp, however it failed when I ran "dhcp" or
> > > "tftp" command in uboot with a tons of:
> > > 
> > > 
> > > ERROR: v7_dcache_inval_range - start address is not aligned - 0x7fb677e0
> > > ERROR: v7_dcache_inval_range - stop address is not aligned - 0x7fb67820
> > 
> > I'm seeing this on Cubieboard2 and Cubietruck. It appears to be down to
> > a change to the upstream designware driver:
> > 
> > commit 50b0df814b0f75c08a3d45a017016a75af3edb5d
> > Author: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
> > Date:   Wed Jan 22 20:49:09 2014 +0400
> > 
> >     net/designware: make driver compatible with data cache
> > 
> >     Up until now this driver only worked with data cache disabled.
> >     To make it work with enabled data cache following changes were
> > required:
> > 
> >      * Flush Tx/Rx buffer descriptors their modification
> >      * Invalidate Tx/Rx buffer descriptors before reading its values
> >      * Flush cache for data passed from CPU to GMAC
> >      * Invalidate cache for data passed from GMAC to CPU
> > 
> > http://git.denx.de/?p=u-boot.git;a=commit;h=50b0df814b0f75c08a3d45a017016a7
> > 5af3edb5d
> > 
> > I suppose this was only tested on some architecture which allows DMA
> > flush/invaidation at a fairly fine granularity (at least down to 4 byte
> > boundaries)
> 
> This was a sheer luck this ever worked. Looking at the entire driver, to fix all 
> your issues with DMA and caches, it would be sufficient to re-align "struct 
> dw_eth_dev" properly.
> 
> See drivers/net/designware.h:
> 1) struct dmamacdescr {} is already __aligned(ARCH_DMA_MINALIGN)
>    => This structure, if aligned in memory to proper boundary, can be flushed/
>       invalidated without problems.
> 2) struct dw_eth_dev {} can be aligned to ANY 4-byte boundary
>    But this structure contains two arrays of struct dmamacdescr {} , which each
>    have their elements' lenght aligned to ARCH_DMA_MINALIGN
> 
> Solution:
> 
> Your patch [1/3] and reorder the structure in designware.h so that the
> struct dmamacdescr tx_mac_descrtable[]
> struct dmamacdescr rx_mac_descrtable[]
> are first and anything that does not need to be aligned follows. This way, the 
> DMA descriptors will always be aligned and you need not worry about the flushes. 
> You don't even need to ROUNDUP their length, since they are already fine.

Unfortunately this isn't sufficient, at least a change in the spirit of
my second patch (to flush the entire descriptor) is also needed, because
flushing just a subfield misaligns things again.

And my patch 3/3 is still needed because it deals with the data itself
and not the descriptors.

So having done all that it doesn't seem that reordering dw_eth_dev is
necessary.

Ian.

[U-Boot] [linux-sunxi] Uboot error: address not aligned in v7_dcache_inval_range

[Marek Vasut]

On Monday, April 28, 2014 at 09:55:46 PM, Ian Campbell wrote:
> On Sat, 2014-04-26 at 20:27 +0200, Marek Vasut wrote:
> > On Saturday, April 19, 2014 at 03:30:14 PM, Ian Campbell wrote:
> > > On Sun, 2014-04-13 at 23:45 -0400, Shixin Zeng wrote:
> > > > Hi,
> > > > 
> > > > I compiled the current u-boot from
> > > > https://github.com/jwrdegoede/u-boot-sunxi.git for cubieboard2, and
> > > > wrote it to the SD card. I was trying to boot the kernel on my
> > > > computer over network by tftp, however it failed when I ran "dhcp" or
> > > > "tftp" command in uboot with a tons of:
> > > > 
> > > > 
> > > > ERROR: v7_dcache_inval_range - start address is not aligned -
> > > > 0x7fb677e0 ERROR: v7_dcache_inval_range - stop address is not
> > > > aligned - 0x7fb67820
> > > 
> > > I'm seeing this on Cubieboard2 and Cubietruck. It appears to be down to
> > > a change to the upstream designware driver:
> > > 
> > > commit 50b0df814b0f75c08a3d45a017016a75af3edb5d
> > > Author: Alexey Brodkin <Alexey.Brodkin@synopsys.com>
> > > Date:   Wed Jan 22 20:49:09 2014 +0400
> > > 
> > >     net/designware: make driver compatible with data cache
> > >     
> > >     Up until now this driver only worked with data cache disabled.
> > >     To make it work with enabled data cache following changes were
> > > 
> > > required:
> > >      * Flush Tx/Rx buffer descriptors their modification
> > >      * Invalidate Tx/Rx buffer descriptors before reading its values
> > >      * Flush cache for data passed from CPU to GMAC
> > >      * Invalidate cache for data passed from GMAC to CPU
> > > 
> > > http://git.denx.de/?p=u-boot.git;a=commit;h=50b0df814b0f75c08a3d45a0170
> > > 16a7 5af3edb5d
> > > 
> > > I suppose this was only tested on some architecture which allows DMA
> > > flush/invaidation at a fairly fine granularity (at least down to 4 byte
> > > boundaries)
> > 
> > This was a sheer luck this ever worked. Looking at the entire driver, to
> > fix all your issues with DMA and caches, it would be sufficient to
> > re-align "struct dw_eth_dev" properly.
> > 
> > See drivers/net/designware.h:
> > 1) struct dmamacdescr {} is already __aligned(ARCH_DMA_MINALIGN)
> > 
> >    => This structure, if aligned in memory to proper boundary, can be
> >    flushed/
> >    
> >       invalidated without problems.
> > 
> > 2) struct dw_eth_dev {} can be aligned to ANY 4-byte boundary
> > 
> >    But this structure contains two arrays of struct dmamacdescr {} ,
> >    which each have their elements' lenght aligned to ARCH_DMA_MINALIGN
> > 
> > Solution:
> > 
> > Your patch [1/3] and reorder the structure in designware.h so that the
> > struct dmamacdescr tx_mac_descrtable[]
> > struct dmamacdescr rx_mac_descrtable[]
> > are first and anything that does not need to be aligned follows. This
> > way, the DMA descriptors will always be aligned and you need not worry
> > about the flushes. You don't even need to ROUNDUP their length, since
> > they are already fine.
> 
> Unfortunately this isn't sufficient, at least a change in the spirit of
> my second patch (to flush the entire descriptor) is also needed, because
> flushing just a subfield misaligns things again.

Ah, true. Your second patch is needed as well, sorry.

> And my patch 3/3 is still needed because it deals with the data itself
> and not the descriptors.

True.

> So having done all that it doesn't seem that reordering dw_eth_dev is
> necessary.

Reordering dw_eth_dev is necessary. Look:

108 struct dmamacdescr {                    // sizeof() = 0x10
109         u32 txrx_status;                // +0x0
110         u32 dmamac_cntl;                // +0x4
111         void *dmamac_addr;              // +0x8
112         struct dmamacdescr *dmamac_next;// +0xc
113 } __aligned(ARCH_DMA_MINALIGN);         // total size = 0x40

217 struct dw_eth_dev {
218         u32 interface;        // +0x0
219         u32 tx_currdescnum;   // +0x4
220         u32 rx_currdescnum;   // +0x8
221 
222         struct dmamacdescr tx_mac_descrtable[CONFIG_TX_DESCR_NUM];//+0xc

You do memalign() to allocate this. The .$interface ends up at address aligned 
to 64byte boundary (aka. it's cache aligned). Now, the structure is naturally 
aligned so tx_mac_descrtable[0] ends up at +0xc offset from the start of the 
structure , am I right ?

If I am wrong, then the compiler considers struct dmamacdescr {} as a one big 
chunk of data aligned to ARCH_DMA_MINALIGN boundary and thus inserts a big slop 
between rx_currdescnum and tx_mac_descrtable[0] to pad it correctly, which is 
not nice.

Reordering the structure will make sure there is no slop and there is no 
posibility of making tx_mac_descrtable unaligned ever.

[U-Boot] [linux-sunxi] Uboot error: address not aligned in v7_dcache_inval_range

[Ian Campbell]

On Mon, 2014-04-28 at 22:21 +0200, Marek Vasut wrote:
> On Monday, April 28, 2014 at 09:55:46 PM, Ian Campbell wrote:
> > So having done all that it doesn't seem that reordering dw_eth_dev is
> > necessary.
> 
> Reordering dw_eth_dev is necessary. Look:

It's certainly desirable, but it's not *necessary*. Anyway, that's just
splitting hairs, I'm going to send a patch (on top of the v2 of this
series) shortly.

Ian.