Hi,
On 11/05/2015 01:46 PM, Sergei Shtylyov wrote:
Hello.
On 11/05/2015 09:53 PM, Bin Liu wrote:
Here are a few changes in musb_h_tx_flush_fifo().
- Refering to 2ccc6d30a (usb: musb: fix bit mask for CSR in
musb_h_tx_flush_fifo()), the datasheet says that MUSB_TXCSR_FLUSHFIFO
is only valid when MUSB_TXCSR_TXPKTRDY is set as well. It means
MUSB_TXCSR_TXPKTRDY should be checked, not set.
Hum, my copy of the MUSBHDRC programmer's guide says about
TXCSR.FlushFIFO in host mode:
<<
The CPU writes a 1 to this bit to flush the latest packet from the
endpoint Tx FIFO. The FIFO pointer is reset, the TxPktRdy bit (below) is
cleared and an interrupt is generated. May be set simultaneously with
TxPktRdy to abort the packet that is currently being loaded into the
FIFO. Note: FlushFIFO should only be used when TxPktRdy is set. At other
times, it may cause data to be corrupted. Also note that, if the FIFO is
double-buffered, FlushFIFO may need to be set twice to completely clear
the FIFO.
>>
So how to interpret this message? FLUSHFIFO and TXPKTRDY should be set
at the same time? If so, I will drop this change in V3.
In either case, musb is unable to flush the tx fifo in urb dequque for
device disconnect, but harmless, so the next two changes are important
to give better user experience.
Thanks,
-Bin.
So I don't think this change is valid.
- It seems to be common that sometimes (if not always) musb is unable
to flush tx fifo during urb dequeue. But it seems to be harmless,
since the tx fifo flush is done again in musb_ep_program() when
re-use the hw_ep.
But the WARN() scares many end users, so change it to dev_dbg().
- applications could queue up many tx urbs, then the 1ms delay could
causes minutes of delay in device disconnect. So remove it to get
better user experience. The 1ms delay does not help the flushing
anyway.
- cleanup the debug code - related to lastcsr.
Signed-off-by: Bin Liu <b-liu@xxxxxx>
---
drivers/usb/musb/musb_host.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index 883a9ad..5db24f2 100644
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -112,22 +112,18 @@ static void musb_h_tx_flush_fifo(struct
musb_hw_ep *ep)
struct musb *musb = ep->musb;
void __iomem *epio = ep->regs;
u16 csr;
- u16 lastcsr = 0;
int retries = 1000;
csr = musb_readw(epio, MUSB_TXCSR);
- while (csr & MUSB_TXCSR_FIFONOTEMPTY) {
- if (csr != lastcsr)
- dev_dbg(musb->controller, "Host TX FIFONOTEMPTY csr:
%02x\n", csr);
- lastcsr = csr;
- csr |= MUSB_TXCSR_FLUSHFIFO | MUSB_TXCSR_TXPKTRDY;
+ while ((csr & MUSB_TXCSR_FIFONOTEMPTY) && (csr &
MUSB_TXCSR_TXPKTRDY)) {
while (csr & (MUSB_TXCSR_FIFONOTEMPTY | MUSB_TXCSR_TXPKTRDY)) {
+ csr |= MUSB_TXCSR_FLUSHFIFO;
No, this clearly contradicts the programmer's guide.
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