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usb: cdns3: gadget: enlarge the TRB ring length

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At Android ADB and MTP use case, it uses f_fs which supports scatter list,
it means one request may need several TRBs for it. Besides, TRB consumes
very fast compared to TRB has prepared for above use case, there are at
most 120 pending requests, the date size is 16KB for each request, so four
TRBs (4KB per TRB) per sg entry at worst case. so we need to enlarge the
TRB ring length to avoid "no free TRB error". Since each TRB only consumes
12 bytes (3 * 32 bits), we enlarge the TRB length to 600, it leaves some
buffers for potential "no free TRB error", and only increases a little
memory cost.

Signed-off-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
This commit is contained in:
Peter Chen 2020-09-10 17:11:30 +08:00 committed by Felipe Balbi
parent d6be7c94f9
commit 71ea88f665
1 changed files with 1 additions and 1 deletions
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2
drivers/usb/cdns3/gadget.h
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@ -966,7 +966,7 @@ struct cdns3_usb_regs {
/*
* USBSS-DEV DMA interface.
*/
#define TRBS_PER_SEGMENT 40
#define TRBS_PER_SEGMENT 600
#define ISO_MAX_INTERVAL 10