On 31.08.2015 21:58, Duc Dang wrote:
On Thu, Aug 20, 2015 at 12:38 PM, Duc Dang <dhdang@xxxxxxx> wrote:
The xhci platform driver needs to work on systems that
either only support 64-bit DMA or only support 32-bit DMA.
Attempt to set a coherent dma mask for 64-bit DMA, and
attempt again with 32-bit DMA if that fails.
[dhdang: regenerate the patch over 4.2-rc5 and address new comments]
Signed-off-by: Mark Langsdorf <mlangsdo@xxxxxxxxxx>
Tested-by: Mark Salter <msalter@xxxxxxxxxx>
Signed-off-by: Duc Dang <dhdang@xxxxxxx>
---
Changes from v6:
-Add WARN_ON if dma_mask is NULL
-Use dma_coerce_mask_and_coherent to assign
dma_mask and coherent_dma_mask
Changes from v5:
-Change comment
-Assign dma_mask to coherent_dma_mask if dma_mask is NULL
to make sure dma_set_mask_and_coherent does not fail prematurely.
Changes from v4:
-None
Changes from v3:
-Re-generate the patch over 4.2-rc5
-No code change.
Changes from v2:
-None
Changes from v1:
-Consolidated to use dma_set_mask_and_coherent
-Got rid of the check against sizeof(dma_addr_t)
drivers/usb/host/xhci-plat.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)
diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 890ad9d..e4c7f9d 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -93,14 +93,19 @@ static int xhci_plat_probe(struct platform_device *pdev)
if (irq < 0)
return -ENODEV;
- /* Initialize dma_mask and coherent_dma_mask to 32-bits */
- ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
- if (ret)
- return ret;
- if (!pdev->dev.dma_mask)
- pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
- else
- dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
+ /* Throw a waring if broken platform code didn't initialize dma_mask */
+ WARN_ON(!pdev->dev.dma_mask);
+ /*
+ * Try setting dma_mask and coherent_dma_mask to 64 bits,
+ * then try 32 bits
+ */
+ ret = dma_coerce_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
+ if (ret) {
+ ret = dma_coerce_mask_and_coherent(&pdev->dev,
+ DMA_BIT_MASK(32));
+ if (ret)
+ return ret;
+ }
hcd = usb_create_hcd(driver, &pdev->dev, dev_name(&pdev->dev));
if (!hcd)
--
1.9.1
Hi Greg, Arnd, Russell,
Do you have any more comment about this patch set?
I'm not sure I fully understand why we need to try the 64 bit DMA mask in platform probe.
As I understood it we just want to have some DMA mask set before calling usb_create_hcd()
to make sure USB core gets the "uses_dma" flag set and dma_set_mask() won't fail because of
missing dev->dma_mask.
The correct DMA mask is set later in xhci_gen_setup()
We also need to make sure the controller supports 64bit addressing capability before setting a 64 bit DMA mask.
(bit 0 in HCCPARAMS)
So for platform devices it goes look go this:
xhci_plat_probe()
usb_create_hcd()
usb_create_shared_hcd()
hcd->self.uses_dma = (dev->dma_mask != NULL);
usb_add_hcd()
hcd->driver->reset() (.reset = xhci_plat_setup)
xhci_plat_setup()
xhci_gen_setup()
if (HCC_64BIT_ADDR(xhci->hcc_params) && !dma_set_mask(dev, DMA_BIT_MASK(64))) {
xhci_dbg(xhci, "Enabling 64-bit DMA addresses.\n");
dma_set_coherent_mask(dev, DMA_BIT_MASK(64));
}
or do we end up with dev->dma_mask = NULL on 64-bit DMA only after trying to set it to 32 in xhci_plat_probe(),
and thus also failing the dma_set_mask() in xhci_gen_setup()?
-Mathias
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