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    usb: musb: introduce api for dma code to check compatibility with usb request · 5f5761cb
    Mian Yousaf Kaukab 提交于
    Gadget MUSB driver handles dma mappings in musb_gadget_queue(). Where as it is
    possible for  dma code to reject the usb request later at ->channel_program()
    called from txstate()/rxstate()
    
    For example ->channel_program in tusb6010_omap.c:
    
    static int tusb_omap_dma_program(struct dma_channel *channel, u16 packet_sz,
            u8 rndis_mode, dma_addr_t dma_addr, u32 len)
    {
    ...
    	if (unlikely(dma_addr & 0x1) || (len < 32) || (len > packet_sz))
    		return false;
    ...
    	if (dma_addr & 0x2)
    		return false;
    ...
    }
    
    In this case, usb request will be handled in PIO mode which renders dma mapping
    operations unnecessary.
    
    This patch adds an api to allow dma code to indicate incompatibility with usb
    request. Gadget musb driver call this api, if available, before dma mappings to
    avoid any unnecessary mapping operations.
    Signed-off-by: NMian Yousaf Kaukab <mian.yousaf.kaukab@stericsson.com>
    Signed-off-by: NFelipe Balbi <balbi@ti.com>
    5f5761cb
musb_gadget.c 55.8 KB