Re: [PATCH v4 08/18] net: davinci_emac: potentially get the MAC address from MTD

[David Lechner]

On 06/29/2018 03:09 PM, David Lechner wrote:
> On 06/29/2018 04:40 AM, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> >
> > On da850-evm board we can read the MAC address from MTD. It's currently
> > done in the relevant board file, but we want to get rid of all the MAC
> > reading callbacks from the board file (SPI and NAND). Move the reading
> > of the MAC address from SPI to the emac driver's probe function.
> >
> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> > ---
> > Â drivers/net/ethernet/ti/davinci_emac.c | 20 ++++++++++++++++++--
> > Â 1 file changed, 18 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/ti/davinci_emac.c b/drivers/net/ethernet/ti/davinci_emac.c
> > index a1a6445b5a7e..48e6a7755811 100644
> > --- a/drivers/net/ethernet/ti/davinci_emac.c
> > +++ b/drivers/net/ethernet/ti/davinci_emac.c
> > @@ -67,7 +67,7 @@
> > Â #include <linux/of_irq.h>
> > Â #include <linux/of_net.h>
> > Â #include <linux/mfd/syscon.h>
> > -
> > +#include <linux/mtd/mtd.h>
> > Â #include <asm/irq.h>
> > Â #include <asm/page.h>
> > @@ -1783,7 +1783,10 @@ static int davinci_emac_probe(struct platform_device *pdev)
> > ÂÂÂÂÂ struct cpdma_params dma_params;
> > ÂÂÂÂÂ struct clk *emac_clk;
> > ÂÂÂÂÂ unsigned long emac_bus_frequency;
> > -
> > +#ifdef CONFIG_MTD
> > +ÂÂÂ size_t mac_addr_len;
> > +ÂÂÂ struct mtd_info *mtd;
> > +#endif /* CONFIG_MTD */
> > ÂÂÂÂÂ /* obtain emac clock from kernel */
> > ÂÂÂÂÂ emac_clk = devm_clk_get(&pdev->dev, NULL);
> > @@ -1815,6 +1818,19 @@ static int davinci_emac_probe(struct platform_device *pdev)
> > ÂÂÂÂÂÂÂÂÂ goto err_free_netdev;
> > ÂÂÂÂÂ }
> > +#ifdef CONFIG_MTD
>
> What about the case when MTD is compiled as a module?
>
> > +ÂÂÂ mtd = get_mtd_device_nm("MAC-Address");
>
> What about the case when PTR_ERR(mtd) == -EPROBE_DEFER?

To answer my own question: because get_mtd_device_nm() doesn't
ever return -EPROBE_DEFER.

I'm trying to make this work on LCDK, but the emac driver probes
before any mtd device is registered, so, I just get -ENODEV even
though I've added a partition to the device tree labeled
"MAC-Address". You can see in the kernel messages that MTD is
not probed until later.

> > +ÂÂÂ if (!IS_ERR(mtd)) {
> > +ÂÂÂÂÂÂÂ rc = mtd_read(mtd, 0, ETH_ALEN,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ &mac_addr_len, priv->mac_addr);
> > +ÂÂÂÂÂÂÂ if (rc == 0)
> > +ÂÂÂÂÂÂÂÂÂÂÂ dev_info(&pdev->dev,
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ "Read MAC addr from SPI Flash: %pM\n",
> > +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ priv->mac_addr);
> > +ÂÂÂÂÂÂÂ put_mtd_device(mtd);
> > +ÂÂÂ }
> > +#endif /* CONFIG_MTD */
> > +
> > ÂÂÂÂÂ /* MAC addr and PHY mask , RMII enable info from platform_data */
> > ÂÂÂÂÂ memcpy(priv->mac_addr, pdata->mac_addr, ETH_ALEN);
> > ÂÂÂÂÂ priv->phy_id = pdata->phy_id;