[BISECT] v3.18-rc1 doesn't boot on nitrogen6x i.MX6 board

[BISECT] v3.18-rc1 doesn't boot on nitrogen6x i.MX6 board

[Fabio Estevam]

Hi Brian,

On Thu, Oct 23, 2014 at 6:30 PM, Brian Downing <bdowning@lavos.net> wrote:
> Hi all; apologies for not posting to the linux-arm-kernel mailing list,
> but lists.infradead.org seems, well, dead:
>
> $ host lists.infradead.org
> Host lists.infradead.org not found: 3(NXDOMAIN)
>
> v3.18-rc1 doesn't boot on my Boundary Devices nitrogen6x board.
> (Specifically, imx6q-nitrogen6x.dtb).  It fails before any console output.
> I bisected it down to this commit:
>
> commit 3fce0e882f61513c45c67e15bd0fde03341b58a5
> Author: Tim Harvey <tharvey@gateworks.com>
> Date:   Thu Aug 7 23:36:40 2014 -0700
>
>     PCI: imx6: Delay enabling reference clock for SS until it stabilizes
>
>     According to the IMX6 reference manuals, REF_SSP_EN (Reference clock enable
>     for SS function) must remain deasserted until the reference clock is
>     running at the appropriate frequency.
>
>     Delay enabling the reference clock for the SS function until it has
>     stabilized.  This prevents a high link failure rate (>5%) on certain IMX6
>     boards at various temperatures.
>
>     [bhelgaas: reword changelog slightly]
>     Tested-by: Fabio Estevam <festevam@gmail.com>
>     Signed-off-by: Tim Harvey <tharvey@gateworks.com>
>     Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
>     Acked-by: Marek Vasut <marex@denx.de>
>     Acked-by: Lucas Stach <l.stach@pengutronix.de>
>
> With that one commit reverted v3.18-rc1 fires up just fine for me.
>
> I really haven't looked into what might be wrong, I just wanted to let
> you know that this fix apparently breaks some boards.

Adding Eric and Troy in case they could comment. I don't know why this
commit would cause failure on nitrogen board.

Regards,

Fabio Estevam

[BISECT] v3.18-rc1 doesn't boot on nitrogen6x i.MX6 board

[Eric Nelson]

Thanks for the report Brian (and Fabio).

On 10/23/2014 01:46 PM, Fabio Estevam wrote:
> Hi Brian,
> 
> On Thu, Oct 23, 2014 at 6:30 PM, Brian Downing <bdowning@lavos.net> wrote:
>> Hi all; apologies for not posting to the linux-arm-kernel mailing list,
>> but lists.infradead.org seems, well, dead:
>>
>> $ host lists.infradead.org
>> Host lists.infradead.org not found: 3(NXDOMAIN)
>>
>> v3.18-rc1 doesn't boot on my Boundary Devices nitrogen6x board.
>> (Specifically, imx6q-nitrogen6x.dtb).  It fails before any console output.
>> I bisected it down to this commit:
>>
>> commit 3fce0e882f61513c45c67e15bd0fde03341b58a5
>> Author: Tim Harvey <tharvey@gateworks.com>
>> Date:   Thu Aug 7 23:36:40 2014 -0700
>>
>>     PCI: imx6: Delay enabling reference clock for SS until it stabilizes
>>
>>     According to the IMX6 reference manuals, REF_SSP_EN (Reference clock enable
>>     for SS function) must remain deasserted until the reference clock is
>>     running at the appropriate frequency.
>>
>>     Delay enabling the reference clock for the SS function until it has
>>     stabilized.  This prevents a high link failure rate (>5%) on certain IMX6
>>     boards at various temperatures.
>>
>>     [bhelgaas: reword changelog slightly]
>>     Tested-by: Fabio Estevam <festevam@gmail.com>
>>     Signed-off-by: Tim Harvey <tharvey@gateworks.com>
>>     Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
>>     Acked-by: Marek Vasut <marex@denx.de>
>>     Acked-by: Lucas Stach <l.stach@pengutronix.de>
>>
>> With that one commit reverted v3.18-rc1 fires up just fine for me.
>>
>> I really haven't looked into what might be wrong, I just wanted to let
>> you know that this fix apparently breaks some boards.

We'll dig in and let you know what we find.

Regards,


Eric

[BISECT] v3.18-rc1 doesn't boot on nitrogen6x i.MX6 board

[Fabio Estevam]

On Thu, Oct 23, 2014 at 6:46 PM, Fabio Estevam <festevam@gmail.com> wrote:

>> I really haven't looked into what might be wrong, I just wanted to let
>> you know that this fix apparently breaks some boards.
>
> Adding Eric and Troy in case they could comment. I don't know why this
> commit would cause failure on nitrogen board.

Ok, so I am able to reproduce this issue on a mx6qsabresd if I don't
pass the PCI gpio reset (like in nitrogen):

--- a/arch/arm/boot/dts/imx6qdl-sabresd.dtsi
+++ b/arch/arm/boot/dts/imx6qdl-sabresd.dtsi
@@ -521,7 +521,6 @@
 &pcie {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_pcie>;
-       reset-gpio = <&gpio7 12 0>;
        status = "okay";
 };


Richard Zhu sent a fix for this, but it has not been applied yet:
http://www.spinics.net/lists/linux-pci/msg34748.html

With his patch applied the kernel can boot fine.

Regards,

Fabio Estevam

[BISECT] v3.18-rc1 doesn't boot on nitrogen6x i.MX6 board

[Eric Nelson]

Thanks Fabio (and Richard).

On 10/23/2014 06:43 PM, Fabio Estevam wrote:
> On Thu, Oct 23, 2014 at 6:46 PM, Fabio Estevam <festevam@gmail.com> wrote:
> 
>>> I really haven't looked into what might be wrong, I just wanted to let
>>> you know that this fix apparently breaks some boards.
>>
>> Adding Eric and Troy in case they could comment. I don't know why this
>> commit would cause failure on nitrogen board.
> 
> Ok, so I am able to reproduce this issue on a mx6qsabresd if I don't
> pass the PCI gpio reset (like in nitrogen):
> 
> --- a/arch/arm/boot/dts/imx6qdl-sabresd.dtsi
> +++ b/arch/arm/boot/dts/imx6qdl-sabresd.dtsi
> @@ -521,7 +521,6 @@
>  &pcie {
>         pinctrl-names = "default";
>         pinctrl-0 = <&pinctrl_pcie>;
> -       reset-gpio = <&gpio7 12 0>;
>         status = "okay";
>  };
> 
> 
> Richard Zhu sent a fix for this, but 	it has not been applied yet:
> http://www.spinics.net/lists/linux-pci/msg34748.html
> 
> With his patch applied the kernel can boot fine.
> 
> Regards,
> 
> Fabio Estevam
>