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From:   Sanket Parmar <sparmar@cadence.com>
To:     Peter Chen <peter.chen@kernel.org>
CC:     Pawel Laszczak <pawell@cadence.com>,
        "a-govindraju@ti.com" <a-govindraju@ti.com>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Rahul Kumar <kurahul@cadence.com>,
        "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
        "kishon@ti.com" <kishon@ti.com>
Subject: RE: [PATCH 1/2] usb: cdns3: Use dma_pool_* api to alloc trb pool
Thread-Topic: [PATCH 1/2] usb: cdns3: Use dma_pool_* api to alloc trb pool
Thread-Index: AQHXFKPdvzUNZxNPcEW/PcjrzJru26qC0CCAgAHHqUA=
Date:   Mon, 15 Mar 2021 06:11:23 +0000
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References: <1615267180-9289-1-git-send-email-sparmar@cadence.com>
 <20210314024951.GD17526@b29397-desktop>
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Hi Peter,
>=20
> On 21-03-09 06:19:39, Sanket Parmar wrote:
> > Allocation of DMA coherent memory in atomic context using
> > dma_alloc_coherent() might fail on platforms with smaller
> > DMA region.
> >
> > To fix it, dma_alloc_coherent() is replaced with dma_pool
> > API to allocate a smaller chunk of DMA coherent memory for
> > TRB rings.
> >
> > Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver")
>=20
> The patch is ok, but I don't think it is a bug-fix, it is an
> improvement for smaller DMA region use case.
>=20
> I will apply it with deletion of above Fixes tag if you have no
> more opinion.
>=20

Please go ahead.

Thanks,
Sanket

> Peter
> > Reported-by: Aswath Govindraju <a-govindraju@ti.com>
> > Signed-off-by: Sanket Parmar <sparmar@cadence.com>
> > ---
> >  drivers/usb/cdns3/cdns3-gadget.c |   42 +++++++++++++++++-------------=
--
> -----
> >  drivers/usb/cdns3/cdns3-gadget.h |    1 +
> >  2 files changed, 20 insertions(+), 23 deletions(-)
> >
> > diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3=
-
> gadget.c
> > index 582bfec..5f51215 100644
> > --- a/drivers/usb/cdns3/cdns3-gadget.c
> > +++ b/drivers/usb/cdns3/cdns3-gadget.c
> > @@ -59,6 +59,7 @@
> >  #include <linux/dma-mapping.h>
> >  #include <linux/usb/gadget.h>
> >  #include <linux/module.h>
> > +#include <linux/dmapool.h>
> >  #include <linux/iopoll.h>
> >
> >  #include "core.h"
> > @@ -190,29 +191,13 @@ dma_addr_t cdns3_trb_virt_to_dma(struct
> cdns3_endpoint *priv_ep,
> >  	return priv_ep->trb_pool_dma + offset;
> >  }
> >
> > -static int cdns3_ring_size(struct cdns3_endpoint *priv_ep)
> > -{
> > -	switch (priv_ep->type) {
> > -	case USB_ENDPOINT_XFER_ISOC:
> > -		return TRB_ISO_RING_SIZE;
> > -	case USB_ENDPOINT_XFER_CONTROL:
> > -		return TRB_CTRL_RING_SIZE;
> > -	default:
> > -		if (priv_ep->use_streams)
> > -			return TRB_STREAM_RING_SIZE;
> > -		else
> > -			return TRB_RING_SIZE;
> > -	}
> > -}
> > -
> >  static void cdns3_free_trb_pool(struct cdns3_endpoint *priv_ep)
> >  {
> >  	struct cdns3_device *priv_dev =3D priv_ep->cdns3_dev;
> >
> >  	if (priv_ep->trb_pool) {
> > -		dma_free_coherent(priv_dev->sysdev,
> > -				  cdns3_ring_size(priv_ep),
> > -				  priv_ep->trb_pool, priv_ep-
> >trb_pool_dma);
> > +		dma_pool_free(priv_dev->eps_dma_pool,
> > +			      priv_ep->trb_pool, priv_ep->trb_pool_dma);
> >  		priv_ep->trb_pool =3D NULL;
> >  	}
> >  }
> > @@ -226,7 +211,7 @@ static void cdns3_free_trb_pool(struct
> cdns3_endpoint *priv_ep)
> >  int cdns3_allocate_trb_pool(struct cdns3_endpoint *priv_ep)
> >  {
> >  	struct cdns3_device *priv_dev =3D priv_ep->cdns3_dev;
> > -	int ring_size =3D cdns3_ring_size(priv_ep);
> > +	int ring_size =3D TRB_RING_SIZE;
> >  	int num_trbs =3D ring_size / TRB_SIZE;
> >  	struct cdns3_trb *link_trb;
> >
> > @@ -234,10 +219,10 @@ int cdns3_allocate_trb_pool(struct
> cdns3_endpoint *priv_ep)
> >  		cdns3_free_trb_pool(priv_ep);
> >
> >  	if (!priv_ep->trb_pool) {
> > -		priv_ep->trb_pool =3D dma_alloc_coherent(priv_dev->sysdev,
> > -						       ring_size,
> > -						       &priv_ep-
> >trb_pool_dma,
> > -						       GFP_DMA32 |
> GFP_ATOMIC);
> > +		priv_ep->trb_pool =3D dma_pool_alloc(priv_dev-
> >eps_dma_pool,
> > +						   GFP_DMA32 |
> GFP_ATOMIC,
> > +						   &priv_ep->trb_pool_dma);
> > +
> >  		if (!priv_ep->trb_pool)
> >  			return -ENOMEM;
> >
> > @@ -3113,6 +3098,7 @@ static void cdns3_gadget_exit(struct cdns *cdns)
> >
> >  	dma_free_coherent(priv_dev->sysdev, 8, priv_dev->setup_buf,
> >  			  priv_dev->setup_dma);
> > +	dma_pool_destroy(priv_dev->eps_dma_pool);
> >
> >  	kfree(priv_dev->zlp_buf);
> >  	usb_put_gadget(&priv_dev->gadget);
> > @@ -3185,6 +3171,14 @@ static int cdns3_gadget_start(struct cdns *cdns)
> >  	/* initialize endpoint container */
> >  	INIT_LIST_HEAD(&priv_dev->gadget.ep_list);
> >  	INIT_LIST_HEAD(&priv_dev->aligned_buf_list);
> > +	priv_dev->eps_dma_pool =3D
> dma_pool_create("cdns3_eps_dma_pool",
> > +						 priv_dev->sysdev,
> > +						 TRB_RING_SIZE, 8, 0);
> > +	if (!priv_dev->eps_dma_pool) {
> > +		dev_err(priv_dev->dev, "Failed to create TRB dma pool\n");
> > +		ret =3D -ENOMEM;
> > +		goto err1;
> > +	}
> >
> >  	ret =3D cdns3_init_eps(priv_dev);
> >  	if (ret) {
> > @@ -3235,6 +3229,8 @@ static int cdns3_gadget_start(struct cdns *cdns)
> >  err2:
> >  	cdns3_free_all_eps(priv_dev);
> >  err1:
> > +	dma_pool_destroy(priv_dev->eps_dma_pool);
> > +
> >  	usb_put_gadget(&priv_dev->gadget);
> >  	cdns->gadget_dev =3D NULL;
> >  	return ret;
> > diff --git a/drivers/usb/cdns3/cdns3-gadget.h b/drivers/usb/cdns3/cdns3=
-
> gadget.h
> > index 21fa461..ecf9b91 100644
> > --- a/drivers/usb/cdns3/cdns3-gadget.h
> > +++ b/drivers/usb/cdns3/cdns3-gadget.h
> > @@ -1298,6 +1298,7 @@ struct cdns3_device {
> >
> >  	struct cdns3_usb_regs		__iomem *regs;
> >
> > +	struct dma_pool			*eps_dma_pool;
> >  	struct usb_ctrlrequest		*setup_buf;
> >  	dma_addr_t			setup_dma;
> >  	void				*zlp_buf;
> > --
> > 1.7.1
> >
>=20
> --
>=20
> Thanks,
> Peter Chen