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Date: Wed, 28 Mar 2018 09:57:29 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Greg Ungerer <gerg@...ux-m68k.org>
Cc: netdev <netdev@...r.kernel.org>,
"Linux/m68k" <linux-m68k@...r.kernel.org>
Subject: Re: [PATCH] net: fec: set dma_coherent_mask
Hi Greg,
On Wed, Mar 28, 2018 at 9:27 AM, Greg Ungerer <gerg@...ux-m68k.org> wrote:
> On 27/03/18 22:59, Geert Uytterhoeven wrote:
>> On Mon, Mar 26, 2018 at 3:36 PM, Greg Ungerer <gerg@...ux-m68k.org> 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 <gerg@...ux-m68k.org>
>>
>> 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 <gerg@...ux-m68k.org>
> ---
> 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@...ux-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
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