2018-07-19 17:22 GMT+02:00 Andrew Lunn <andrew@xxxxxxx>:
> On Wed, Jul 18, 2018 at 06:10:34PM +0200, Bartosz Golaszewski wrote:
>> From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
>>
>> Many non-DT platforms read the MAC address from EEPROM. Usually it's
>> either done with callbacks defined in board files or from SoC-specific
>> ethernet drivers.
>>
>> In order to generalize this, try to read the MAC from nvmem in
>> eth_platform_get_mac_address() using a standard lookup name:
>> "mac-address".
>>
>> Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
>> ---
>> net/ethernet/eth.c | 29 +++++++++++++++++++++++++++++
>> 1 file changed, 29 insertions(+)
>>
>> diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
>> index 6b64586fd2af..adf5bd03851f 100644
>> --- a/net/ethernet/eth.c
>> +++ b/net/ethernet/eth.c
>> @@ -54,6 +54,7 @@
>> #include <linux/if_ether.h>
>> #include <linux/of_net.h>
>> #include <linux/pci.h>
>> +#include <linux/nvmem-consumer.h>
>> #include <net/dst.h>
>> #include <net/arp.h>
>> #include <net/sock.h>
>> @@ -530,7 +531,10 @@ int eth_platform_get_mac_address(struct device *dev, u8 *mac_addr)
>> struct device_node *dp = dev_is_pci(dev) ?
>> pci_device_to_OF_node(to_pci_dev(dev)) : dev->of_node;
>> const unsigned char *addr = NULL;
>> + unsigned char addrbuf[ETH_ALEN];
>> + struct nvmem_cell *nvmem;
>> const char *from = NULL;
>> + size_t alen;
>>
>> if (dp) {
>> addr = of_get_mac_address(dp);
>> @@ -544,6 +548,31 @@ int eth_platform_get_mac_address(struct device *dev, u8 *mac_addr)
>> from = "arch callback";
>> }
>>
>> + if (!addr) {
>> + nvmem = nvmem_cell_get(dev, "mac-address");
>> + if (IS_ERR(nvmem) && PTR_ERR(nvmem) == -EPROBE_DEFER)
>
> How does EPROBE_DEFER work here? You say the use case is
> Non-DT. Without having DT, how do you know the cell should exist, but
> does not yet exist? I might be looking at old code, but i only see
> -EPROBE_DEFER inside the if (np) case.
>
>> + /* We may have a lookup registered for MAC address but
>> + * the corresponding nvmem provider hasn't been
>> + * registered yet.
>> + */
>> + return -EPROBE_DEFER;
>
> You really should return real errors. If i'm reading
> __nvmem_device_get() right, it will return a NULL pointer when the
> cell does not exist. NULL is not an error, so IS_ERR() will return
> false. So you should return all errors from nvmem_cell_get().
>
> Andrew
We have a patch queued for nvmem for 4.19 which adds a notion of nvmem
cell lookups similar to gpio lookups:
https://patchwork.kernel.org/patch/10496045/
This will work fine with probe deferral.
Bart
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