On 07/26/2018 06:52 PM, Grygorii Strashko wrote:
>
>
> On 07/23/2018 05:16 PM, Robin Murphy wrote:
>> Now that we can track upstream DMA constraints properly with
>> bus_dma_mask instead of trying (and failing) to maintain it in
>> coherent_dma_mask, it doesn't make much sense for the firmware code to
>> be touching the latter at all. It's merely papering over bugs wherein a
>> driver has failed to call dma_set_coherent_mask() *and* the bus code has
>> not initialised any default value.
>>
>> We don't really want to encourage more drivers coercing dma_mask so
>> we'll continue to fix that up if necessary, but add a warning to help
>> flush out any such buggy bus code that remains.
>>
>> CC: Rob Herring <robh+dt@xxxxxxxxxx>
>> CC: Frank Rowand <frowand.list@xxxxxxxxx>
>> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
>> ---
>> drivers/of/device.c | 20 ++++++++++----------
>> 1 file changed, 10 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/of/device.c b/drivers/of/device.c
>> index 0d39633e8545..5957cd4fa262 100644
>> --- a/drivers/of/device.c
>> +++ b/drivers/of/device.c
>> @@ -127,20 +127,20 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
>> }
>>
>> /*
>> - * Set default coherent_dma_mask to 32 bit. Drivers are expected to
>> - * setup the correct supported mask.
>> + * If @dev is expected to be DMA-capable then the bus code that created
>> + * it should have initialised its dma_mask pointer by this point. For
>> + * now, we'll continue the legacy behaviour of coercing it to the
>> + * coherent mask if not, but we'll no longer do so quietly.
>> */
>> - if (!dev->coherent_dma_mask)
>> - dev->coherent_dma_mask = DMA_BIT_MASK(32);
>> - /*
>> - * Set it to coherent_dma_mask by default if the architecture
>> - * code has not set it.
>> - */
>> - if (!dev->dma_mask)
>> + if (!dev->dma_mask) {
>> + dev_warn(dev, "DMA mask not set\n");
>> dev->dma_mask = &dev->coherent_dma_mask;
>> + }
>>
>> - if (!size)
>> + if (!size && dev->coherent_dma_mask)
>> size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
>> + else if (!size)
>> + size = 1ULL << 32;
>>
>> dev->dma_pfn_offset = offset;
>>
>>
>
> the result of this change is pretty strange as for me :(
> Resulted code:
>
> /*
> * If @dev is expected to be DMA-capable then the bus code that created
> * it should have initialised its dma_mask pointer by this point. For
> * now, we'll continue the legacy behaviour of coercing it to the
> * coherent mask if not, but we'll no longer do so quietly.
> */
> if (!dev->dma_mask) {
> dev_warn(dev, "DMA mask not set\n");
> dev->dma_mask = &dev->coherent_dma_mask;
> ^this will always produce warning in case of platform-bus or if there are no bus driver.
> even if DT contains correct definition of dma-range
> }
>
> if (!size && dev->coherent_dma_mask)
>
> ^ coherent_dma_mask is zero, so size will not be calculated
pls, ignore this particular comment
> size = max(dev->coherent_dma_mask, dev->coherent_dma_mask + 1);
> else if (!size)
> size = 1ULL << 32;
>
> dev->dma_pfn_offset = offset;
>
> /*
> * Limit coherent and dma mask based on size and default mask
> * set by the driver.
> */
> mask = DMA_BIT_MASK(ilog2(dma_addr + size - 1) + 1);
> dev->bus_dma_mask = mask;
> dev->coherent_dma_mask &= mask;
>
> ^^ if nobody set coherent_dma_mask before it will stay null forever unless drivers
> will overwrite it. Again even if DT has correct definition for dma-range.
>
> *dev->dma_mask &= mask;
>
> coherent = of_dma_is_coherent(np);
> dev_dbg(dev, "device is%sdma coherent\n",
> coherent ? " " : " not ");
>
>
FYI, with below diff i can boot at least:
diff --git a/drivers/of/device.c b/drivers/of/device.c
index 5957cd4..f7dc121 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -150,8 +150,8 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
*/
mask = DMA_BIT_MASK(ilog2(dma_addr + size - 1) + 1);
dev->bus_dma_mask = mask;
- dev->coherent_dma_mask &= mask;
- *dev->dma_mask &= mask;
+ dev->coherent_dma_mask = mask;
+ *dev->dma_mask = mask;
coherent = of_dma_is_coherent(np);
dev_dbg(dev, "device is%sdma coherent\n",
--
regards,
-grygorii
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