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

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Date:   Fri, 5 May 2017 10:28:17 +0300
From:   Peter Ujfalusi <peter.ujfalusi@...com>
To:     Tony Lindgren <tony@...mide.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



On 2017-05-04 17:31, Tony Lindgren wrote:
> * 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;

note for myself: this only works with g_ncm. I was using g_cdc, switched 
to g_ether, then to g_ncm.
However... If I revert this series and add this line, the ethernet will 
not work at all, I can not ping the n810 and it will not get the nfsroot 
either (next-20170503).

only f_ncm.c does:
	ncm->port.no_skb_reserve =
		gadget_avoids_skb_reserve(cdev->gadget);

>  	/* Normal reset, as B-Device;
>  	 * or else after HNP, as A-Device
>

- Péter