From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Subject: Re: [PATCH] net: fec: set dma_coherent_mask Date: Wed, 28 Mar 2018 09:57:29 +0200 Message-ID: References: <1522071386-29743-1-git-send-email-gerg@linux-m68k.org> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: Sender: netdev-owner@vger.kernel.org To: Greg Ungerer Cc: netdev , Linux/m68k List-Id: linux-m68k@vger.kernel.org Hi Greg, On Wed, Mar 28, 2018 at 9:27 AM, Greg Ungerer wrote: > On 27/03/18 22:59, Geert Uytterhoeven wrote: >> On Mon, Mar 26, 2018 at 3:36 PM, Greg Ungerer wrote: >>> As of commit 205e1b7f51e4 ("dma-mapping: warn when there is no >>> coherent_dma_mask") the Freescale FEC driver is issuing the following >>> warning on driver initialization on ColdFire systems: >>> >>> WARNING: CPU: 0 PID: 1 at ./include/linux/dma-mapping.h:516 0x40159e20 >>> Modules linked in: >>> CPU: 0 PID: 1 Comm: swapper Not tainted 4.16.0-rc7-dirty #4 >>> Stack from 41833dd8: >>> 41833dd8 40259c53 40025534 40279e26 00000003 00000000 4004e514 41827000 >>> 400255de 40244e42 00000204 40159e20 00000009 00000000 00000000 4024531d >>> 40159e20 40244e42 00000204 00000000 00000000 00000000 00000007 00000000 >>> 00000000 40279e26 4028d040 40226576 4003ae88 40279e26 418273f6 41833ef8 >>> 7fffffff 418273f2 41867028 4003c9a2 4180ac6c 00000004 41833f8c 4013e71c >>> 40279e1c 40279e26 40226c16 4013ced2 40279e26 40279e58 4028d040 00000000 >>> Call Trace: >>> [<40025534>] 0x40025534 >>> [<4004e514>] 0x4004e514 >>> [<400255de>] 0x400255de >>> [<40159e20>] 0x40159e20 >>> [<40159e20>] 0x40159e20 >>> >>> It is not fatal, the driver and the system continue to function normally. >>> >>> As per the warning the coherent_dma_mask is not set on this device. >>> There is nothing special about the DMA memory coherency on this hardware >>> so we can just set the mask to 32bits during probe. >>> >>> Signed-off-by: Greg Ungerer >> >> Thanks for your patch! >> >>> --- >>> drivers/net/ethernet/freescale/fec_main.c | 2 ++ >>> 1 file changed, 2 insertions(+) >>> >>> Is this the best way to handle this problem? >>> Comments welcome... >>> >>> diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c >>> index d4604bc..3cb130a 100644 >>> --- a/drivers/net/ethernet/freescale/fec_main.c >>> +++ b/drivers/net/ethernet/freescale/fec_main.c >>> @@ -2702,6 +2702,8 @@ static int fec_enet_alloc_queue(struct net_device *ndev) >>> int ret = 0; >>> struct fec_enet_priv_tx_q *txq; >>> >>> + dma_set_coherent_mask(&fep->pdev->dev, DMA_BIT_MASK(32)); >>> + >>> for (i = 0; i < fep->num_tx_queues; i++) { >>> txq = kzalloc(sizeof(*txq), GFP_KERNEL); >>> if (!txq) { >> >> As per your other email, this does not trigger on iMX systems using DT. >> Hence I'm wondering if the Coldfire platform code shouldn't just do the >> same what drivers/of/device.c does, cfr. >> https://www.spinics.net/lists/linux-m68k/msg10929.html? > > I had been thinking that all along, but I couldn't see how to set this when > there was no real bus involved that would have configured this. Turns out > for platform devices you can set it as part of the platform setup. So now > the patch becomes specific to the ColdFire and FEC ethernet devices. > > Regards > Greg > > --- > > [PATCH] m68k: set dma and coherent masks for platform FEC ethernets > > As of commit 205e1b7f51e4 ("dma-mapping: warn when there is no > coherent_dma_mask") the Freescale FEC driver is issuing the following > warning on driver initialization on ColdFire systems: > > WARNING: CPU: 0 PID: 1 at ./include/linux/dma-mapping.h:516 0x40159e20 > Modules linked in: > CPU: 0 PID: 1 Comm: swapper Not tainted 4.16.0-rc7-dirty #4 > Stack from 41833dd8: > 41833dd8 40259c53 40025534 40279e26 00000003 00000000 4004e514 41827000 > 400255de 40244e42 00000204 40159e20 00000009 00000000 00000000 4024531d > 40159e20 40244e42 00000204 00000000 00000000 00000000 00000007 00000000 > 00000000 40279e26 4028d040 40226576 4003ae88 40279e26 418273f6 41833ef8 > 7fffffff 418273f2 41867028 4003c9a2 4180ac6c 00000004 41833f8c 4013e71c > 40279e1c 40279e26 40226c16 4013ced2 40279e26 40279e58 4028d040 00000000 > Call Trace: > [<40025534>] 0x40025534 > [<4004e514>] 0x4004e514 > [<400255de>] 0x400255de > [<40159e20>] 0x40159e20 > [<40159e20>] 0x40159e20 > > It is not fatal, the driver and the system continue to function normally. > > As per the warning the coherent_dma_mask is not set on this device. > There is nothing special about the DMA memory coherency on this hardware > so we can just set the mask to 32bits in the platform data for the FEC > ethernet devices. > > Signed-off-by: Greg Ungerer > --- > arch/m68k/coldfire/device.c | 14 ++++++++++++-- > 1 file changed, 12 insertions(+), 2 deletions(-) > > diff --git a/arch/m68k/coldfire/device.c b/arch/m68k/coldfire/device.c > index 84938fd..f93e0e5 100644 > --- a/arch/m68k/coldfire/device.c > +++ b/arch/m68k/coldfire/device.c > @@ -130,12 +130,18 @@ > }, > }; > > +static u64 mcf_dma_mask = DMA_BIT_MASK(32); > + > static struct platform_device mcf_fec0 = { > .name = FEC_NAME, > .id = 0, > .num_resources = ARRAY_SIZE(mcf_fec0_resources), > .resource = mcf_fec0_resources, > - .dev.platform_data = FEC_PDATA, > + .dev = { > + .dma_mask = &mcf_dma_mask, Can you make this &mcf_fec0.dev.coherent_dma_mask, removing the need for mcf_dma_mask, or doesn't C allow that? > + .coherent_dma_mask = DMA_BIT_MASK(32), > + .platform_data = FEC_PDATA, > + } > }; > > #ifdef MCFFEC_BASE1 > @@ -167,7 +173,11 @@ > .id = 1, > .num_resources = ARRAY_SIZE(mcf_fec1_resources), > .resource = mcf_fec1_resources, > - .dev.platform_data = FEC_PDATA, > + .dev = { > + .dma_mask = &mcf_dma_mask, Likewise. > + .coherent_dma_mask = DMA_BIT_MASK(32), > + .platform_data = FEC_PDATA, > + } Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds