Re: [PATCH 1/3] phy: rockchip: emmc: Enable pulldown for strobe line

[Dragan Simic]

Hello Conor and Folker,

On 2024-03-26 20:46, Conor Dooley wrote:
> On Tue, Mar 26, 2024 at 07:54:35PM +0100, Folker Schwesinger via B4 
> Relay wrote:
> > From: Folker Schwesinger <dev@xxxxxxxxxxxxxxxxxxxxx>
> >
> > Restore the behavior of the Rockchip kernel that undconditionally
> > enables the internal strobe pulldown.
>
> What do you mean "restore the behaviour of the rockchip kernel"? Did
> mainline behave the same as the rockchip kernel previously? If not,
> using "restore" here is misleading. "Unconditionally" is also 
> incorrect,
> because you have a property that disables it.
>
> > As the DT property rockchip,enable-strobe-pulldown is obsolete now,
> > replace it with a property to disable the internal pulldown.
> >
> > This fixes I/O errors observed on various Rock Pi 4 and NanoPi4 series
> > boards with some eMMC modules. Other boards may also be affected.
> >
> > An example of these errors is as follows:
> >
> > [  290.060817] mmc1: running CQE recovery
> > [  290.061337] blk_update_request: I/O error, dev mmcblk1, sector 
> > 1411072 op 0x1:(WRITE) flags 0x800 phys_seg 36 prio class 0
> > [  290.061370] EXT4-fs warning (device mmcblk1p1): ext4_end_bio:348: 
> > I/O error 10 writing to inode 29547 starting block 176466)
> > [  290.061484] Buffer I/O error on device mmcblk1p1, logical block 
> > 172288
> >
> > Fixes: 8b5c2b45b8f0 ("phy: rockchip: set pulldown for strobe line in 
> > dts")
> > Signed-off-by: Folker Schwesinger <dev@xxxxxxxxxxxxxxxxxxxxx>
> > ---
> >  drivers/phy/rockchip/phy-rockchip-emmc.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c 
> > b/drivers/phy/rockchip/phy-rockchip-emmc.c
> > index 20023f6eb994..6e637f3e1b19 100644
> > --- a/drivers/phy/rockchip/phy-rockchip-emmc.c
> > +++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
> > @@ -376,14 +376,14 @@ static int rockchip_emmc_phy_probe(struct 
> > platform_device *pdev)
> >  	rk_phy->reg_offset = reg_offset;
> >  	rk_phy->reg_base = grf;
> >  	rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
> > -	rk_phy->enable_strobe_pulldown = PHYCTRL_REN_STRB_DISABLE;
> > +	rk_phy->enable_strobe_pulldown = PHYCTRL_REN_STRB_ENABLE;
> >  	rk_phy->output_tapdelay_select = PHYCTRL_OTAPDLYSEL_DEFAULT;
> >
> >  	if (!of_property_read_u32(dev->of_node, "drive-impedance-ohm", 
> > &val))
> >  		rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
> >
> > -	if (of_property_read_bool(dev->of_node, 
> > "rockchip,enable-strobe-pulldown"))
> > -		rk_phy->enable_strobe_pulldown = PHYCTRL_REN_STRB_ENABLE;
> > +	if (of_property_read_bool(dev->of_node, 
> > "rockchip,disable-strobe-pulldown"))
> > +		rk_phy->enable_strobe_pulldown = PHYCTRL_REN_STRB_DISABLE;
>
> Unfortunately you cannot do this.
> Previously no property at all meant disabled and a property was 
> required
> to enable it. With this change the absence of a property means that it
> will be enabled.
> An old devicetree is that wanted this to be disabled would have no
> property and will now end up with it enabled. This is an ABI break and 
> is
> clearly not backwards compatible, that's a NAK unless it is 
> demonstrable
> that noone actually wants to disable it at all.

Moreover, as I already explained some time ago, [1] some boards and
devices are unfortunately miswired, and we don't want to enable the
DATA STROBE pull-down on such boards.

[1] 
https://lore.kernel.org/linux-rockchip/ca5b7cad01f645c7c559ab26a8db8085@xxxxxxxxxxx/#t

> If this patch fixes a problem on a board that you have, I would suggest
> that you add the property to enable it, as the binding tells you to.
>
> Thanks,
> Conor.
>
> >  	if (!of_property_read_u32(dev->of_node, 
> > "rockchip,output-tapdelay-select", &val)) {
> >  		if (val <= PHYCTRL_OTAPDLYSEL_MAXVALUE)
> >
> > --
> > 2.44.0
>
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