linux-kernel - Re: [PATCH 0/4] usb: musb: tusb6010

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Date:   Thu, 4 May 2017 07:31:45 -0700
From:   Tony Lindgren <tony@...mide.com>
To:     Peter Ujfalusi <peter.ujfalusi@...com>
Cc:     b-liu@...com, gregkh@...uxfoundation.org,
        linux-usb@...r.kernel.org, linux-omap@...r.kernel.org,
        balbi@...nel.org, linux-kernel@...r.kernel.org,
        Aaro Koskinen <aaro.koskinen@....fi>
Subject: Re: [PATCH 0/4] usb: musb: tusb6010_omap: Convert to DMAengine

* Peter Ujfalusi <peter.ujfalusi@...com> [170503 04:00]:
> Hi,
> 
> With port_window support implemented in DMAengine and the sDMA DMAengine driver,
> the tusb6010_omap driver can be converted away from the custom legacy omap-dma
> API to generic DMAengine.
> 
> The first two patch is to prepare the tusb6010_omap driver for the conversion.
> The third one adds the needed entries for the dma_slave_map so we can request
> the DMA channels. This can be reverted when the stack is converted to DT.
> 
> The last patch does the main work to move the driver to DMAengine API.
> 
> I have tested the set on top of next-20170503 on Nokia n810 with nfsroot using
> CDC Ethernet (g_cdc) and copying files with scp to/form my host.

Thanks for doing this! For this series:

Acked-by: Tony Lindgren <tony@...mide.com>

> To force that the DMA is actually used I have:
> diff --git a/drivers/usb/musb/tusb6010_omap.c b/drivers/usb/musb/tusb6010_omap.c
> index 05aefcad40b5..a5fc2a6bdad3 100644
> --- a/drivers/usb/musb/tusb6010_omap.c
> +++ b/drivers/usb/musb/tusb6010_omap.c
> @@ -216,8 +216,8 @@ static int tusb_omap_dma_program(struct dma_channel *channel, u16 packet_sz,
>  	 * use a timer for the callback, but it is unsafe as the XFR_SIZE
>  	 * register is corrupt, and we won't know if the DMA worked.
>  	 */
> -	if (dma_addr & 0x2)
> -		return false;
> +// 	if (dma_addr & 0x2)
> +// 		return false;
>  
>  	/*
>  	 * Because of HW issue #10, it seems like mixing sync DMA and async
> 
> Since this condition will almost all the time was true - effectively disabling
> the DMA use.

Yeah this really should have the transfers aligned to 32-bit like
the production kernel did. For reference, the following should do
the trick but of course would have to be done conditionally.

Regards,

Tony

8< ----------------------
diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
--- a/drivers/usb/musb/musb_gadget.c
+++ b/drivers/usb/musb/musb_gadget.c
@@ -2153,6 +2153,7 @@ __acquires(musb->lock)
 	musb->g.a_alt_hnp_support = 0;
 	musb->g.a_hnp_support = 0;
 	musb->g.quirk_zlp_not_supp = 1;
+	musb->g.quirk_avoids_skb_reserve = 1;
 
 	/* Normal reset, as B-Device;
 	 * or else after HNP, as A-Device