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

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Date: Tue, 26 Mar 2024 20:55:40 +0100
From: Dragan Simic <dsimic@...jaro.org>
To: Conor Dooley <conor@...nel.org>
Cc: dev@...ker-schwesinger.de, Vinod Koul <vkoul@...nel.org>, Kishon Vijay
 Abraham I <kishon@...nel.org>, Heiko Stuebner <heiko@...ech.de>, Chris Ruehl
 <chris.ruehl@...ys.com.hk>, Rob Herring <robh@...nel.org>, Krzysztof
 Kozlowski <krzysztof.kozlowski+dt@...aro.org>, Conor Dooley
 <conor+dt@...nel.org>, Christopher Obbard <chris.obbard@...labora.com>,
 Alban Browaeys <alban.browaeys@...il.com>, Doug Anderson
 <dianders@...omium.org>, Brian Norris <briannorris@...omium.org>, Jensen
 Huang <jensenhuang@...endlyarm.com>, linux-phy@...ts.infradead.org,
 linux-arm-kernel@...ts.infradead.org, linux-rockchip@...ts.infradead.org,
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH 1/3] phy: rockchip: emmc: Enable pulldown for strobe line

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@...ker-schwesinger.de>
>> 
>> 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 As the DT property rockchip,enable-strobe-pulldown is obsolete now,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@...ker-schwesinger.de>
>> ---
>>  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@manjaro.org/#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
>> 
>> 
> 
> _______________________________________________
> Linux-rockchip mailing list
> Linux-rockchip@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-rockchip

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