Hi Marek, Thanks for the feedback.
> Subject: Re: [PATCH] net: ravb: Fix NULL pointer access > > On 9/18/20 5:26 PM, Biju Das wrote: > [...] > > >>>>> +++ b/drivers/net/ravb.c > >>>>> @@ -438,7 +438,8 @@ static int ravb_config(struct udevice *dev) > >>>>> > >>>>> writel(mask, eth->iobase + RAVB_REG_ECMR); > >>>>> > >>>>> -phy->drv->writeext(phy, -1, 0x02, 0x08, (0x0f << 5) | 0x19); > >>>>> +if (phy->drv->writeext) > >>>>> +phy->drv->writeext(phy, -1, 0x02, 0x08, (0x0f << 5) | 0x19); > >>>> > >>>> Shouldn't we rather move this into the PHY driver altogether ? > >>> > >>> If I fix, the phydriver with empty function, compiler will complain > >>> about > >> unused parameter right? > >>> What about other phy's which doesn't have this callback. > >> > >> I mean, should we not move this entire code which configures > >> something in a Micrel PHY, and is specific to Micrel PHY, into the > >> Micrel PHY driver and remove the whole call of writeext from this > ethernet driver ? > > > > Ok , this function is invoked during data transfer. > > The ravb_config() is invoked when starting the interface, see ravb_start(), it > is not repeatedly called during data transfer. Yep you are correct , it will be called during starting of the interface. I have seen the crash when I started doing tftp or ping, which in turn calls ravb_start. > > We could remove this function and test on all RCar boards to see any issues > present or not? > > No, because calling the writeext configures something in the Micrel > KSZ90x1 PHY, and by removing it, I suspect the Micrel PHY would stop > working. I agree, otherwise it will use default values which may cause issues. > > By looking at [1], only this driver is using writeext. > > [1]https://elixir.bootlin.com/u-boot/v2020.10-rc4/A/ident/writeext > > git grep indicates a couple more sites where the writeext is called. > But look into the KSZ9031 datasheet, that particular writeext call seems to be > setting up RGMII Clock Pad Skew (MMD Address 2, Register 8), and I think > there is a matching DT binding to set those up too, rxc-skew-ps and txc- > skew-ps I think. Thanks for the pointers. I checked the configs[2] which uses renesas ravb driver and found that we are defining only rxc-skew-ps in all dts. since CONFIG DM_ETH is defined it is already picking the value corresponding to "rxc-skew-ps". For txc-skew-ps anyway the value is default one. So we don't care. > So I think if you set those two DT properties in rcar2/3 DTs accordingly (and > that might already be the case, but please double-check), you can even drop > this entire writeext altogether. I did a grep and the below configs enables renesas ravb driver .Only Gen3 uses renesas ravb driver and all of them have "rxc-skew-ps" in Devicetree. So I agree with you, it is safe to remove writephyext. I will post V2, removing this [2] u-boot/configs/rcar3_ulcb_defconfig:CONFIG_RENESAS_RAVB=y u-boot/configs/r8a77990_ebisu_defconfig:CONFIG_RENESAS_RAVB=y u-boot/configs/r8a774a1_beacon_defconfig:CONFIG_RENESAS_RAVB=y u-boot/configs/hihope_rzg2_defconfig:CONFIG_RENESAS_RAVB=y u-boot/configs/r8a77995_draak_defconfig:CONFIG_RENESAS_RAVB=y u-boot/configs/r8a77970_eagle_defconfig:CONFIG_RENESAS_RAVB=y u-boot/configs/rcar3_salvator-x_defconfig:CONFIG_RENESAS_RAVB=y Cheers, Biju Renesas Electronics Europe GmbH, Geschaeftsfuehrer/President: Carsten Jauch, Sitz der Gesellschaft/Registered office: Duesseldorf, Arcadiastrasse 10, 40472 Duesseldorf, Germany, Handelsregister/Commercial Register: Duesseldorf, HRB 3708 USt-IDNr./Tax identification no.: DE 119353406 WEEE-Reg.-Nr./WEEE reg. no.: DE 14978647
