Date:	Thu, 14 Apr 2016 11:02:40 +0300
From:	Felipe Balbi <balbi@...nel.org>
To:	changbin.du@...el.com
Cc:	gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Du\, Changbin" <changbin.du@...el.com>
Subject: Re: [PATCH v4 2/2] usb: dwc3: add debugfs node to dump FIFO/Queue available space


Hi,

changbin.du@...el.com writes:
> From: "Du, Changbin" <changbin.du@...el.com>
>
> For DWC3 USB controller, the Global Debug Queue/FIFO Space Available
> Register(GDBGFIFOSPACE) can be used to dump FIFO/Queue available space.
> This can be used to check some special issues, like whether data is
> successfully copied from memory to fifo when a trb is blocked.
>
> Signed-off-by: Du, Changbin <changbin.du@...el.com>
> ---
> v4:
>   Do not fail silently, but print error.
>
> ---
>  drivers/usb/dwc3/core.h    |  5 +++++
>  drivers/usb/dwc3/debugfs.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 49 insertions(+)
>
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 6254b2f..899cf76 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -348,6 +348,11 @@
>  #define DWC3_DSTS_LOWSPEED		(2 << 0)
>  #define DWC3_DSTS_FULLSPEED1		(3 << 0)
>  
> +/* Global Debug Queue/FIFO Space Available Register */
> +#define DWC3_GDBGFIFOSPACE_NUM(x)	(((x) << 0) & 0x1F)
> +#define DWC3_GDBGFIFOSPACE_TYPE(x)	(((x) << 5) & 0xE0)
> +#define DWC3_GDBGFIFOSPACE_GET_SPACE(x)	(((x) >> 16) & 0xFFFF)

we always use lower case hex numbers. Also, databook refers to top 16
bits as "Space Avaiable" so I'd prefer that you called this macro:

	DWC3_GDBGFIFOSPACE_SPACE_AVAILABLE(x)

as that will aid with grepping

> diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
> index 615d4dc..83e5bc1 100644
> --- a/drivers/usb/dwc3/debugfs.c
> +++ b/drivers/usb/dwc3/debugfs.c
> @@ -426,6 +426,45 @@ static const struct file_operations dwc3_mode_fops = {
>  	.release		= single_release,
>  };
>  
> +static int dwc3_fifo_show(struct seq_file *s, void *unused)

you call this file 'fifo' however you print more than just the
fifos. You printk the request queues, info queue, descriptor fetch
queue, event queue and protocol status queue.

It seems, to me, you're trying to do way too much in a single file.

> +{
> +	struct dwc3		*dwc = s->private;
> +	unsigned long		flags;
> +	unsigned int		type, index;
> +	const char		*name;
> +	u32			reg;
> +
> +	static const char * const fifo_names[] = {
> +		"TxFIFO", "RxFIFO", "TxReqQ", "RxReqQ", "RxInfoQ",
> +		"DescFetchQ", "EventQ", "ProtocolStatusQ"};
> +	spin_lock_irqsave(&dwc->lock, flags);
> +	for (type = 0; type < 8; type++) {

type < ARRAY_SIZE(fifo_names) ??

> +		name = fifo_names[type];
> +		for (index = 0; index < 32; index++) {

not *all* dwc3 implementations enable all 32 endpoints, that's why we
have dwc->num_endpoints

> +			dwc3_writel(dwc->regs, DWC3_GDBGFIFOSPACE,
> +				DWC3_GDBGFIFOSPACE_NUM(index) |
> +				DWC3_GDBGFIFOSPACE_TYPE(type));
> +			reg = dwc3_readl(dwc->regs, DWC3_GDBGFIFOSPACE);

this writel() followed by a readl() could be a nice little helper
function in core.c. Remember that we need the FIFO Space and link state
to make sure we're allowed to start a transfer ;-)

I'd suggesting adding the following to core.c:

int dwc3_core_fifo_space(struct dwc3_ep *dep, unsigned int type)
{
	u32 reg;

        dwc3_writel(dwc->regs, DWC3_GDBGFIFOSPACE,
        	DWC3_GDBGFIFOSPACE_NUM(dep->number) |
                DWC3_GDBGFIFOSPACE_TYPE(type));

	reg = dwc3_readl(dwc->regs, DWC3_GDBGFIFOSPACE);

	return DWC3_GDBGFIFOSPACE_SPACE_AVAILABLE(reg);
}

then, add the prototype to core.h. (both of these in a separate patch).

Then $subject just uses that helper to print out the data you want to
print. I still think we might be better off with one file per type (iow
TX fifo file, RX fifo file, TX request queue file, and so on).

In fact, we could actually have a per-endpoint directory where all of
these details are printed out in a much more structured form. If you
want, I can work on that, no problem, but you're also welcome to
implement it yourself and I'd be around to help as needed.

In summary, we should have our debugfs looking like so:

./ep0
./ep0/descriptor_fetch_queue
./ep0/event_queue
./ep0/info_queue
./ep0/protocol_status_queue
./ep0/request_queue
./ep0/rx_fifo
./ep0/rx_request_queue
./ep0/tx_fifo
./ep0/tx_request_queue
./ep1
./ep10
./ep10/descriptor_fetch_queue
./ep10/event_queue
./ep10/info_queue
./ep10/protocol_status_queue
./ep10/request_queue
./ep10/rx_fifo
./ep10/rx_request_queue
./ep10/tx_fifo
./ep10/tx_request_queue
./ep11
./ep11/descriptor_fetch_queue
./ep11/event_queue
./ep11/info_queue
./ep11/protocol_status_queue
./ep11/request_queue
./ep11/rx_fifo
./ep11/rx_request_queue
./ep11/tx_fifo
./ep11/tx_request_queue
./ep12
./ep12/descriptor_fetch_queue
./ep12/event_queue
./ep12/info_queue
./ep12/protocol_status_queue
./ep12/request_queue
./ep12/rx_fifo
./ep12/rx_request_queue
./ep12/tx_fifo
./ep12/tx_request_queue
./ep13
./ep13/descriptor_fetch_queue
./ep13/event_queue
./ep13/info_queue
./ep13/protocol_status_queue
./ep13/request_queue
./ep13/rx_fifo
./ep13/rx_request_queue
./ep13/tx_fifo
./ep13/tx_request_queue
./ep14
./ep14/descriptor_fetch_queue
./ep14/event_queue
./ep14/info_queue
./ep14/protocol_status_queue
./ep14/request_queue
./ep14/rx_fifo
./ep14/rx_request_queue
./ep14/tx_fifo
./ep14/tx_request_queue
./ep15
./ep15/descriptor_fetch_queue
./ep15/event_queue
./ep15/info_queue
./ep15/protocol_status_queue
./ep15/request_queue
./ep15/rx_fifo
./ep15/rx_request_queue
./ep15/tx_fifo
./ep15/tx_request_queue
./ep16
./ep16/descriptor_fetch_queue
./ep16/event_queue
./ep16/info_queue
./ep16/protocol_status_queue
./ep16/request_queue
./ep16/rx_fifo
./ep16/rx_request_queue
./ep16/tx_fifo
./ep16/tx_request_queue
./ep17
./ep17/descriptor_fetch_queue
./ep17/event_queue
./ep17/info_queue
./ep17/protocol_status_queue
./ep17/request_queue
./ep17/rx_fifo
./ep17/rx_request_queue
./ep17/tx_fifo
./ep17/tx_request_queue
./ep18
./ep18/descriptor_fetch_queue
./ep18/event_queue
./ep18/info_queue
./ep18/protocol_status_queue
./ep18/request_queue
./ep18/rx_fifo
./ep18/rx_request_queue
./ep18/tx_fifo
./ep18/tx_request_queue
./ep19
./ep19/descriptor_fetch_queue
./ep19/event_queue
./ep19/info_queue
./ep19/protocol_status_queue
./ep19/request_queue
./ep19/rx_fifo
./ep19/rx_request_queue
./ep19/tx_fifo
./ep19/tx_request_queue
./ep1/descriptor_fetch_queue
./ep1/event_queue
./ep1/info_queue
./ep1/protocol_status_queue
./ep1/request_queue
./ep1/rx_fifo
./ep1/rx_request_queue
./ep1/tx_fifo
./ep1/tx_request_queue
./ep2
./ep20
./ep20/descriptor_fetch_queue
./ep20/event_queue
./ep20/info_queue
./ep20/protocol_status_queue
./ep20/request_queue
./ep20/rx_fifo
./ep20/rx_request_queue
./ep20/tx_fifo
./ep20/tx_request_queue
./ep21
./ep21/descriptor_fetch_queue
./ep21/event_queue
./ep21/info_queue
./ep21/protocol_status_queue
./ep21/request_queue
./ep21/rx_fifo
./ep21/rx_request_queue
./ep21/tx_fifo
./ep21/tx_request_queue
./ep22
./ep22/descriptor_fetch_queue
./ep22/event_queue
./ep22/info_queue
./ep22/protocol_status_queue
./ep22/request_queue
./ep22/rx_fifo
./ep22/rx_request_queue
./ep22/tx_fifo
./ep22/tx_request_queue
./ep23
./ep23/descriptor_fetch_queue
./ep23/event_queue
./ep23/info_queue
./ep23/protocol_status_queue
./ep23/request_queue
./ep23/rx_fifo
./ep23/rx_request_queue
./ep23/tx_fifo
./ep23/tx_request_queue
./ep24
./ep24/descriptor_fetch_queue
./ep24/event_queue
./ep24/info_queue
./ep24/protocol_status_queue
./ep24/request_queue
./ep24/rx_fifo
./ep24/rx_request_queue
./ep24/tx_fifo
./ep24/tx_request_queue
./ep25
./ep25/descriptor_fetch_queue
./ep25/event_queue
./ep25/info_queue
./ep25/protocol_status_queue
./ep25/request_queue
./ep25/rx_fifo
./ep25/rx_request_queue
./ep25/tx_fifo
./ep25/tx_request_queue
./ep26
./ep26/descriptor_fetch_queue
./ep26/event_queue
./ep26/info_queue
./ep26/protocol_status_queue
./ep26/request_queue
./ep26/rx_fifo
./ep26/rx_request_queue
./ep26/tx_fifo
./ep26/tx_request_queue
./ep27
./ep27/descriptor_fetch_queue
./ep27/event_queue
./ep27/info_queue
./ep27/protocol_status_queue
./ep27/request_queue
./ep27/rx_fifo
./ep27/rx_request_queue
./ep27/tx_fifo
./ep27/tx_request_queue
./ep28
./ep28/descriptor_fetch_queue
./ep28/event_queue
./ep28/info_queue
./ep28/protocol_status_queue
./ep28/request_queue
./ep28/rx_fifo
./ep28/rx_request_queue
./ep28/tx_fifo
./ep28/tx_request_queue
./ep29
./ep29/descriptor_fetch_queue
./ep29/event_queue
./ep29/info_queue
./ep29/protocol_status_queue
./ep29/request_queue
./ep29/rx_fifo
./ep29/rx_request_queue
./ep29/tx_fifo
./ep29/tx_request_queue
./ep2/descriptor_fetch_queue
./ep2/event_queue
./ep2/info_queue
./ep2/protocol_status_queue
./ep2/request_queue
./ep2/rx_fifo
./ep2/rx_request_queue
./ep2/tx_fifo
./ep2/tx_request_queue
./ep3
./ep30
./ep30/descriptor_fetch_queue
./ep30/event_queue
./ep30/info_queue
./ep30/protocol_status_queue
./ep30/request_queue
./ep30/rx_fifo
./ep30/rx_request_queue
./ep30/tx_fifo
./ep30/tx_request_queue
./ep31
./ep31/descriptor_fetch_queue
./ep31/event_queue
./ep31/info_queue
./ep31/protocol_status_queue
./ep31/request_queue
./ep31/rx_fifo
./ep31/rx_request_queue
./ep31/tx_fifo
./ep31/tx_request_queue
./ep3/descriptor_fetch_queue
./ep3/event_queue
./ep3/info_queue
./ep3/protocol_status_queue
./ep3/request_queue
./ep3/rx_fifo
./ep3/rx_request_queue
./ep3/tx_fifo
./ep3/tx_request_queue
./ep4
./ep4/descriptor_fetch_queue
./ep4/event_queue
./ep4/info_queue
./ep4/protocol_status_queue
./ep4/request_queue
./ep4/rx_fifo
./ep4/rx_request_queue
./ep4/tx_fifo
./ep4/tx_request_queue
./ep5
./ep5/descriptor_fetch_queue
./ep5/event_queue
./ep5/info_queue
./ep5/protocol_status_queue
./ep5/request_queue
./ep5/rx_fifo
./ep5/rx_request_queue
./ep5/tx_fifo
./ep5/tx_request_queue
./ep6
./ep6/descriptor_fetch_queue
./ep6/event_queue
./ep6/info_queue
./ep6/protocol_status_queue
./ep6/request_queue
./ep6/rx_fifo
./ep6/rx_request_queue
./ep6/tx_fifo
./ep6/tx_request_queue
./ep7
./ep7/descriptor_fetch_queue
./ep7/event_queue
./ep7/info_queue
./ep7/protocol_status_queue
./ep7/request_queue
./ep7/rx_fifo
./ep7/rx_request_queue
./ep7/tx_fifo
./ep7/tx_request_queue
./ep8
./ep8/descriptor_fetch_queue
./ep8/event_queue
./ep8/info_queue
./ep8/protocol_status_queue
./ep8/request_queue
./ep8/rx_fifo
./ep8/rx_request_queue
./ep8/tx_fifo
./ep8/tx_request_queue
./ep9
./ep9/descriptor_fetch_queue
./ep9/event_queue
./ep9/info_queue
./ep9/protocol_status_queue
./ep9/request_queue
./ep9/rx_fifo
./ep9/rx_request_queue
./ep9/tx_fifo
./ep9/tx_request_queue
./link_state
./mode
./regdump
./testmode

-- 
balbi

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