linux-kernel - Re: [PATCH v2] r8169: set coherent DMA mask as well as streaming DMA mask

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Message-Id: <6D7D95BB-DE3E-48E0-ACDA-8E1C58875F79@linaro.org>
Date:   Fri, 14 Oct 2016 14:46:53 +0100
From:   Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:     David Laight <David.Laight@...LAB.COM>
Cc:     "romieu@...zoreil.com" <romieu@...zoreil.com>,
        "nic_swsd@...ltek.com" <nic_swsd@...ltek.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "davem@...emloft.net" <davem@...emloft.net>
Subject: Re: [PATCH v2] r8169: set coherent DMA mask as well as streaming DMA mask



> On 14 Oct 2016, at 14:42, David Laight<David.Laight@...LAB.COM> wrote:
> 
> From: Of Ard Biesheuvel
>> Sent: 14 October 2016 14:41
>> PCI devices that are 64-bit DMA capable should set the coherent
>> DMA mask as well as the streaming DMA mask. On some architectures,
>> these are managed separately, and so the coherent DMA mask will be
>> left at its default value of 32 if it is not set explicitly. This
>> results in errors such as
>> 
>>     r8169 Gigabit Ethernet driver 2.3LK-NAPI loaded
>>     hwdev DMA mask = 0x00000000ffffffff, dev_addr = 0x00000080fbfff000
>>     swiotlb: coherent allocation failed for device 0000:02:00.0 size=4096
>>     CPU: 0 PID: 1062 Comm: systemd-udevd Not tainted 4.8.0+ #35
>>     Hardware name: AMD Seattle/Seattle, BIOS 10:53:24 Oct 13 2016
>> 
>> on systems without memory that is 32-bit addressable by PCI devices.
>> 
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
>> ---
>> v2: dropped the hunk that sets the coherent DMA mask to DMA_BIT_MASK(32),
>>    which is unnecessary given that it is the default
>> 
>> drivers/net/ethernet/realtek/r8169.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/net/ethernet/realtek/r8169.c b/drivers/net/ethernet/realtek/r8169.c
>> index e55638c7505a..bf000d819a21 100644
>> --- a/drivers/net/ethernet/realtek/r8169.c
>> +++ b/drivers/net/ethernet/realtek/r8169.c
>> @@ -8273,7 +8273,8 @@ static int rtl_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
>>    if ((sizeof(dma_addr_t) > 4) &&
>>        (use_dac == 1 || (use_dac == -1 && pci_is_pcie(pdev) &&
>>                  tp->mac_version >= RTL_GIGA_MAC_VER_18)) &&
>> -        !pci_set_dma_mask(pdev, DMA_BIT_MASK(64))) {
>> +        !pci_set_dma_mask(pdev, DMA_BIT_MASK(64)) &&
>> +        !pci_set_consistent_dma_mask(pdev, DMA_BIT_MASK(64))) {
> 
> Isn't there a dma_set_mask_and_coherent() function ?
> 
>    David
>