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Commit c28f8259 authored by Felipe Balbi's avatar Felipe Balbi
Browse files

usb: dwc3: switch trb enqueue/dequeue and first_trb_index to u8 



We *know* that we have 1 PAGE (4096 bytes) for our
TRB poll. We also know the size of each TRB and know
that we can fit 256 of them in one PAGE. By using a
u8 type we can make sure that:

	enqueue++ % 256;

gets optimized to an increment only.

Signed-off-by: default avatarFelipe Balbi <felipe.balbi@linux.intel.com>
parent 5ef68c56

drivers/usb/dwc3/core.h

+13 −3
Original line number Diff line number Diff line
@@ -470,8 +470,6 @@ struct dwc3_ep { 


	struct dwc3_trb		*trb_pool;

	dma_addr_t		trb_pool_dma;

	u32			trb_enqueue;

	u32			trb_dequeue;

	const struct usb_ss_ep_comp_descriptor *comp_desc;

	struct dwc3		*dwc;
@@ -487,6 +485,18 @@ struct dwc3_ep { 
	/* This last one is specific to EP0 */

#define DWC3_EP0_DIR_IN		(1 << 31)



	/*

	 * IMPORTANT: we *know* we have 256 TRBs in our @trb_pool, so we will

	 * use a u8 type here. If anybody decides to increase number of TRBs to

	 * anything larger than 256 - I can't see why people would want to do

	 * this though - then this type needs to be changed.

	 *

	 * By using u8 types we ensure that our % operator when incrementing

	 * enqueue and dequeue get optimized away by the compiler.

	 */

	u8			trb_enqueue;

	u8			trb_dequeue;



	u8			number;

	u8			type;

	u8			resource_index;
@@ -641,8 +651,8 @@ struct dwc3_request { 
	struct usb_request	request;

	struct list_head	list;

	struct dwc3_ep		*dep;

	u32			first_trb_index;



	u8			first_trb_index;

	u8			epnum;

	struct dwc3_trb		*trb;

	dma_addr_t		trb_dma;