Dear Marek Vasut,
> Dear Benoît Thébaudeau,
>
> > Relax the qTD transfer alignment constraints in order to need less
> > qTDs for
> > buffers that are aligned to 512 bytes but not to pages.
> >
> > Signed-off-by: Benoît Thébaudeau <benoit.thebaud...@advansee.com>
> > Cc: Marek Vasut <ma...@denx.de>
> > Cc: Ilya Yanok <ilya.ya...@cogentembedded.com>
> > Cc: Stefan Herbrechtsmeier <ste...@herbrechtsmeier.net>
> > ---
> > Changes for v2: N/A.
> > Changes for v3:
> > - New patch.
> >
> > .../drivers/usb/host/ehci-hcd.c | 68
> > +++++++++++--------- 1 file changed, 38 insertions(+), 30
> > deletions(-)
> >
> > diff --git u-boot-usb-8d5fb14.orig/drivers/usb/host/ehci-hcd.c
> > u-boot-usb-8d5fb14/drivers/usb/host/ehci-hcd.c index
> > 84c7d08..37517cb
> > 100644
> > --- u-boot-usb-8d5fb14.orig/drivers/usb/host/ehci-hcd.c
> > +++ u-boot-usb-8d5fb14/drivers/usb/host/ehci-hcd.c
> > @@ -215,7 +215,7 @@ ehci_submit_async(struct usb_device *dev,
> > unsigned long
> > pipe, void *buffer, volatile struct qTD *vtd;
> > unsigned long ts;
> > uint32_t *tdp;
> > - uint32_t endpt, token, usbsts;
> > + uint32_t endpt, maxpacket, token, usbsts;
> > uint32_t c, toggle;
> > uint32_t cmd;
> > int timeout;
> > @@ -230,6 +230,7 @@ ehci_submit_async(struct usb_device *dev,
> > unsigned long
> > pipe, void *buffer, le16_to_cpu(req->value),
> > le16_to_cpu(req->value),
> > le16_to_cpu(req->index));
> >
> > +#define PKT_ALIGN 512
>
> Make this const int maybe ?
Why? I don't see any need for this.
> > /*
> > * The USB transfer is split into qTD transfers. Eeach qTD
> > transfer is
> > * described by a transfer descriptor (the qTD). The qTDs form a
> > linked
> > @@ -251,43 +252,41 @@ ehci_submit_async(struct usb_device *dev,
> > unsigned
> > long pipe, void *buffer, if (length > 0 || req == NULL) {
> > /*
> > * Determine the qTD transfer size that will be used for the
> > - * data payload (not considering the final qTD transfer, which
> > - * may be shorter).
> > + * data payload (not considering the first qTD transfer, which
> > + * may be longer or shorter, and the final one, which may be
> > + * shorter).
> > *
> > * In order to keep each packet within a qTD transfer, the qTD
> > - * transfer size is aligned to EHCI_PAGE_SIZE, which is a
> > - * multiple of wMaxPacketSize (except in some cases for
> > - * interrupt transfers, see comment in submit_int_msg()).
> > + * transfer size is aligned to PKT_ALIGN, which is a multiple of
> > + * wMaxPacketSize (except in some cases for interrupt transfers,
> > + * see comment in submit_int_msg()).
> > *
> > - * By default, i.e. if the input buffer is page-aligned,
> > + * By default, i.e. if the input buffer is aligned to PKT_ALIGN,
> > * QT_BUFFER_CNT full pages will be used.
> > */
> > int xfr_sz = QT_BUFFER_CNT;
> > /*
> > - * However, if the input buffer is not page-aligned, the qTD
> > - * transfer size will be one page shorter, and the first qTD
> > + * However, if the input buffer is not aligned to PKT_ALIGN, the
> > + * qTD transfer size will be one page shorter, and the first qTD
> > * data buffer of each transfer will be page-unaligned.
> > */
> > - if ((uint32_t)buffer & (EHCI_PAGE_SIZE - 1))
> > + if ((uint32_t)buffer & (PKT_ALIGN - 1))
> > xfr_sz--;
> > /* Convert the qTD transfer size to bytes. */
> > xfr_sz *= EHCI_PAGE_SIZE;
> > /*
> > - * Determine the number of qTDs that will be required for the
> > - * data payload. This value has to be rounded up since the final
> > - * qTD transfer may be shorter than the regular qTD transfer
> > - * size that has just been computed.
> > + * Approximate by excess the number of qTDs that will be
> > + * required for the data payload. The exact formula is way more
> > + * complicated and saves at most 2 qTDs, i.e. a total of 128
> > + * bytes.
> > */
> > - qtd_count += DIV_ROUND_UP(length, xfr_sz);
> > - /* ZLPs also need a qTD. */
> > - if (!qtd_count)
> > - qtd_count++;
> > + qtd_count += 2 + length / xfr_sz;
> > }
> > /*
> > - * Threshold value based on the worst-case total size of the qTDs
> > to
> > allocate - * for a mass-storage transfer of 65535 blocks of 512
> > bytes.
> > + * Threshold value based on the worst-case total size of the
> > allocated
> > qTDs for + * a mass-storage transfer of 65535 blocks of 512 bytes.
> > */
> > -#if CONFIG_SYS_MALLOC_LEN <= 128 * 1024
> > +#if CONFIG_SYS_MALLOC_LEN <= 64 + 128 * 1024
> > #warning CONFIG_SYS_MALLOC_LEN may be too small for EHCI
> > #endif
> > qtd = memalign(USB_DMA_MINALIGN, qtd_count * sizeof(struct qTD));
> > @@ -314,9 +313,10 @@ ehci_submit_async(struct usb_device *dev,
> > unsigned
> > long pipe, void *buffer, qh->qh_link =
> > cpu_to_hc32((uint32_t)qh_list |
> > QH_LINK_TYPE_QH);
> > c = (usb_pipespeed(pipe) != USB_SPEED_HIGH &&
> > usb_pipeendpoint(pipe) == 0);
> > + maxpacket = usb_maxpacket(dev, pipe);
> > endpt = (8 << QH_ENDPT1_RL) |
> > (c << QH_ENDPT1_C) |
> > - (usb_maxpacket(dev, pipe) << QH_ENDPT1_MAXPKTLEN) |
> > + (maxpacket << QH_ENDPT1_MAXPKTLEN) |
>
> Is this change really needed? (not that I care much).
It's here only to avoid calling the usb_maxpacket() function several times for
nothing since it is also called later in the patch.
> [...]
>
> Took me a bit to make it through, but I think I get it ... just real
> nits above.
OK. Tell me if you have any question.
I don't think any change is needed, all the more you have already applied this
patch.
Best regards,
Benoît
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