usb: dwc3: debugfs: Dump internal states
Hi,
Quoted 17 lines · Thinh Nguyen
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-0+static int dwc3_internal_states_show(struct seq_file *s, void *unused) +{ + struct dwc3 *dwc = s->private; + unsigned int current_mode; + unsigned long flags; + u32 reg; + + spin_lock_irqsave(&dwc->lock, flags);Quoted 8 lines
Review
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-0+ reg = dwc3_readl(dwc->regs, DWC3_GSTS); + current_mode = DWC3_GSTS_CURMOD(reg); + + reg = dwc3_readl(dwc->regs, DWC3_GDBGBMU); + spin_unlock_irqrestore(&dwc->lock, flags); + + seq_printf(s, "GDBGBMU = 0x%08x\n", reg);shouldn't the print be done with locks held?
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I think the lock for the prints should be held at a higher level. Otherwise, I don't think it will make a difference using
dwc->lock.
what happens if this gets preempted when you release the lock and a different thread writes to internal_states and reads the result before $this thread?
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Review
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-0+static ssize_t dwc3_internal_states_write(struct file *file, + const char __user *ubuf, size_t count, loff_t *ppos)why is this necessary? Seems like it would be nicer to create a directory structure if the current operating mode is host so that we don't need to write anything.
Can you clarify more about the directory structure? Actually, I was wondering what's the best way to do this also. The reason I want to write to it is because the LSP selection for host is quite large (2^14).
right, turn each of those into a directory of its own. If you don't want to or can't disclose proper names for those directories, just call them lsp0, lsp1, lsp2, and so on. Then a read of the file under lsp1 directory would write and read the correct registers.
Everything remains read-only.
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It doesn't make sense to dump everything if the controller is in host mode. So I force the user to write a specific LSP selection to dump at a time.
you can just as well force the use to read a file under a specific directory. And if that same user really wants to read everything, it's easy to do so with a simple loop to cat every file under every directory.
Now, if directories would have a single file under, then you may decide to, instead, create a single directory named e.g. lsp and put several files under it. It's a matter of how much information you need to dump.
cheers