Hi all,
I am busy debugging a problem with the i.MX51 FEC ethernet driver, that
stopped working after upgrading u-boot. Before the upgrade I used
v2010.06-rc3, which worked fine.
I gave up on trying to find the difference beween the old version and this one
that broke it.... due to BSP issues, git bisecting seems a monumental task I
am not considering yet.
The funny part is that it seems to work fine if I disable data-caches!
With data caches enabled, it hangs in the following while loop in fec_send(),
at line 592:
...
584 /*
585 * Enable SmartDMA transmit task
586 */
587 fec_tx_task_enable(fec);
588
589 /*
590 * wait until frame is sent .
591 */
592 while (readw(&fec->tbd_base[fec->tbd_index].status) &
FEC_TBD_READY) {
593 udelay(1);
594 }
...
If I change this code in the following way, the while loop exits successfully:
...
584 /*
585 * Enable SmartDMA transmit task
586 */
587 flush_cache(&fec->tbd_base[fec->tbd_index], 4);
588 fec_tx_task_enable(fec);
589 flash_dcache_all();
590
591 /*
592 * wait until frame is sent .
593 */
594 while (readw(&fec->tbd_base[fec->tbd_index].status) &
FEC_TBD_READY) {
595 udelay(1);
596 }
...
Notice the cache flush calls at line 587 and 589. With these, sending
succeeds. The driver still hangs in receiving afterwards, but at least this
part seems to work. If I remove either of the two added lines, it stops
working again.
What is going on here? Why did this work with caches enabled before??
Best regards,
--
David Jander
Protonic Holland.
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