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From: Andrey Smirnov <andrew.smirnov@gmail.com>
To: Ahmad Fatoum <a.fatoum@pengutronix.de>
Cc: Barebox List <barebox@lists.infradead.org>,
	Raphael Poggi <poggi.raph@gmail.com>,
	pza@pengutronix.de
Subject: Re: [PATCH v2 1/5] clk: imx6: remove quirky clk_set_parent(LDB_diN_sel, pll5_video_div)
Date: Sun, 26 May 2019 14:55:36 -0700	[thread overview]
Message-ID: <CAHQ1cqHnqQoUes2FoDgODkJdtFBFwk30r9ZnYm3BvjUwB0RyLQ@mail.gmail.com> (raw)
In-Reply-To: <20190521155626.9906-2-a.fatoum@pengutronix.de>

On Tue, May 21, 2019 at 8:56 AM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote:
>
> barebox has inherited the clk_set_parent(ldb_diN_sel, pll5_video_div)
> from upstream kernel commit 32f3b8da22 ("ARM i.MX6q: set the LDB serial
> clock parent to the video PLL"), where it was enabled for all i.MX6Q
> revisions after 1.0. It was applied whenever CONFIG_DRIVER_VIDEO_IMX_IPUV3
> was defined.
>
> The kernel removed this reparenting again as a preventive measure
> against ERR009219 in 03d576f202 ("clk: imx6: Make the LDB_DI0 and
> LDB_DI1 clocks read-only").
>
> As the kernel used the device tree compatible, which is the same
> for e.g. i.MX6Solo and DualLite, but barebox queried ANATOP which
> lists different CPU types for i.MX6Solo and DualLite and because
> i.MX6QuadPlus wasn't supported at first, barebox grew to do
> the reparenting on the odd set of:
>   - Quad and Dual rev >1.0
>   - DualLite
>   - Solo rev >1.0
>   - QuadPlus and DualPlus rev >1.0
>
> On all of these, except for the QuadPlus and the DualPlus, this
> reparenting may glitch the LDB so that it permanently locks up.
>
> By removing the reparenting in this commit, producing this glitch is
> avoided, unless the device tree[1] reinstates the old behavior:
>
>         &clks {
>                 assigned-clocks = <&clks IMX6QDL_CLK_LDB_DI0_SEL>,
>                                   <&clks IMX6QDL_CLK_LDB_DI1_SEL>;
>                 assigned-clock-parents = <&clks IMX6QDL_CLK_PLL5_VIDEO_DIV>,
>                                          <&clks IMX6QDL_CLK_PLL5_VIDEO_DIV>;
>         };
>
> Follow-up patches will explicitly check for this and do the reparenting
> in a glitch-free manner.
>
> As of v2019.03.0, following mainline boards are potentially broken
> by this (i.e. they're supported by barebox, are in the list above,
> had a LDB enabled and might be defining CONFIG_DRIVER_VIDEO_IMX_IPUV3):
>   - imx6qdl-zii-rdu2.dtsi

This particular patch does break a non 6Q+ version of RDU2,  but the
follow up ones in the series fix it, so it seems that no action is
really necessary on my part.

Thanks,
Andrey Smirnov

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  parent reply	other threads:[~2019-05-26 21:55 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-21 15:56 [PATCH v2 0/5] clk: imx6: work around LDB hang caused by ERR009219 Ahmad Fatoum
2019-05-21 15:56 ` [PATCH v2 1/5] clk: imx6: remove quirky clk_set_parent(LDB_diN_sel, pll5_video_div) Ahmad Fatoum
2019-05-23 10:01   ` Philipp Zabel
2019-05-23 10:28     ` Ahmad Fatoum
2019-05-26 21:55   ` Andrey Smirnov [this message]
2019-05-27  6:29     ` Ahmad Fatoum
2019-05-27  6:50       ` Andrey Smirnov
2019-05-27  7:23         ` Ahmad Fatoum
2019-05-27  7:28           ` Andrey Smirnov
2019-05-27  7:49             ` Ahmad Fatoum
2019-05-27  8:02               ` Andrey Smirnov
2019-05-27  9:19                 ` Ahmad Fatoum
2019-05-27  7:25         ` Andrey Smirnov
2019-05-27  7:39           ` Ahmad Fatoum
2019-05-21 15:56 ` [PATCH v2 2/5] clk: imx6: Make the LDB_DI0 and LDB_DI1 clocks read-only Ahmad Fatoum
2019-05-23 10:01   ` Philipp Zabel
2019-05-27  7:01   ` Andrey Smirnov
2019-05-27  7:38     ` Ahmad Fatoum
2019-05-21 15:56 ` [PATCH v2 3/5] clk: imx6: Mask mmdc_ch1 handshake for periph2_sel and mmdc_ch1_axi_podf Ahmad Fatoum
2019-05-23 10:01   ` Philipp Zabel
2019-05-21 15:56 ` [PATCH v2 4/5] clk: imx6: Fix procedure to switch the parent of LDB_DI_CLK Ahmad Fatoum
2019-05-23 10:03   ` Philipp Zabel
2019-05-26 21:58   ` Andrey Smirnov
2019-05-27  7:04   ` Andrey Smirnov
2019-05-21 15:56 ` [PATCH v2 5/5] clk: imx6: define an enum for ldb mux inputs Ahmad Fatoum
2019-05-23 10:03   ` Philipp Zabel
2019-05-23 10:35     ` Ahmad Fatoum
2019-05-26 21:59 ` [PATCH v2 0/5] clk: imx6: work around LDB hang caused by ERR009219 Andrey Smirnov

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