Re: [PATCH 1/5] soc: imx: imx8m-blk-ctrl: Fix imx8mm mipi reset

Adam Ford
2021-11-05T14:21:51Z

On Fri, Nov 5, 2021 at 9:01 AM Lucas Stach <l.stach@pengutronix.de> wrote:
>
> Hi Adam,
>
> Am Freitag, dem 05.11.2021 um 08:42 -0500 schrieb Adam Ford:
> > Most of the blk-ctrl reset bits are found in one register, however
> > there are two bits in offset 8 for pulling the MIPI DPHY out of reset
> > and these need to be set when IMX8MM_DISPBLK_PD_MIPI_CSI is brought
> > out of reset or the MIPI_CSI hangs.
> >
> I'm undecided yet if I like this solution, as register 0x8 has
> different content on different instances of the blk-ctrl, so naming it
> mipi_rst_mask is confusing for others.

Both Mini and Nano use it, so I could add a comment that this
register only applies to Mini and Nano. For all others, it would be
empty and do nothing anyway. If you have a name you'd prefer, I can
do that.

>
> My initial thought was that we should habe a MIPI PHY driver
> controlling all the registers in the disp-blk-ctrl, other than SFT_RSTN
> and CLK_EN, however I see how the reset handling for the PHY would then
> be inconsistent with how we handle all the other devices in the disp-
> blk domain. But then the HW guys seemed to think along the same lines,
> as they placed the PHY resets into the PHY registers, instead of the
> SFT_RSTN, which had more than enough spare bits to carry those
> resets...

The NXP ATF code sets these bits in the GPC code with the other power
domain stuff, so it seems like they intended it to be used as a power
domain thing and not MIPI PHY driver.

>
> > Fixes: 926e57c065df ("soc: imx: imx8m-blk-ctrl: add DISP blk-ctrl")
> > Signed-off-by: Adam Ford <aford173@gmail.com>
> > ---
> > drivers/soc/imx/imx8m-blk-ctrl.c | 6 ++++++
> > 1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/soc/imx/imx8m-blk-ctrl.c b/drivers/soc/imx/imx8m-blk-ctrl.c
> > index 519b3651d1d9..5506bd075c35 100644
> > --- a/drivers/soc/imx/imx8m-blk-ctrl.c
> > +++ b/drivers/soc/imx/imx8m-blk-ctrl.c
> > @@ -17,6 +17,7 @@
> >
> > #define BLK_SFT_RSTN 0x0
> > #define BLK_CLK_EN 0x4
> > +#define BLK_MIPI_RESET_DIV 0x8
> >
> > struct imx8m_blk_ctrl_domain;
> >
> > @@ -36,6 +37,7 @@ struct imx8m_blk_ctrl_domain_data {
> > const char *gpc_name;
> > u32 rst_mask;
> > u32 clk_mask;
> > + u32 mipi_rst_mask;
> > };
> >
> > #define DOMAIN_MAX_CLKS 3
> > @@ -78,6 +80,7 @@ static int imx8m_blk_ctrl_power_on(struct generic_pm_domain *genpd)
> >
> > /* put devices into reset */
> > regmap_clear_bits(bc->regmap, BLK_SFT_RSTN, data->rst_mask);
> > + regmap_clear_bits(bc->regmap, BLK_MIPI_RESET_DIV, data->mipi_rst_mask);
> >
> > /* enable upstream and blk-ctrl clocks to allow reset to propagate */
> > ret = clk_bulk_prepare_enable(data->num_clks, domain->clks);
> > @@ -99,6 +102,7 @@ static int imx8m_blk_ctrl_power_on(struct generic_pm_domain *genpd)
> >
> > /* release reset */
> > regmap_set_bits(bc->regmap, BLK_SFT_RSTN, data->rst_mask);
> > + regmap_set_bits(bc->regmap, BLK_MIPI_RESET_DIV, data->mipi_rst_mask);
> >
> > /* disable upstream clocks */
> > clk_bulk_disable_unprepare(data->num_clks, domain->clks);
> > @@ -122,6 +126,7 @@ static int imx8m_blk_ctrl_power_off(struct generic_pm_domain *genpd)
> > /* put devices into reset and disable clocks */
> > regmap_clear_bits(bc->regmap, BLK_SFT_RSTN, data->rst_mask);
> > regmap_clear_bits(bc->regmap, BLK_CLK_EN, data->clk_mask);
> > + regmap_clear_bits(bc->regmap, BLK_MIPI_RESET_DIV, data->mipi_rst_mask);
>
> For consistency the reset assertion should be put before the clock
> disable.

I can do that. How do you want me to proceed?

adam

>
> Regards,
> Lucas
>
> >
> > /* power down upstream GPC domain */
> > pm_runtime_put(domain->power_dev);
> > @@ -488,6 +493,7 @@ static const struct imx8m_blk_ctrl_domain_data imx8mm_disp_blk_ctl_domain_data[]
> > .gpc_name = "mipi-csi",
> > .rst_mask = BIT(3) | BIT(4),
> > .clk_mask = BIT(10) | BIT(11),
> > + .mipi_rst_mask = BIT(16) | BIT(17),
> > },
> > };
> >
>
>