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    Subject[PATCH 5.8 178/232] clk: bcm2835: Do not use prediv with bcm2711s PLLs
    Date
    From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>

    [ Upstream commit f34e4651ce66a754f41203284acf09b28b9dd955 ]

    Contrary to previous SoCs, bcm2711 doesn't have a prescaler in the PLL
    feedback loop. Bypass it by zeroing fb_prediv_mask when running on
    bcm2711.

    Note that, since the prediv configuration bits were re-purposed, this
    was triggering miscalculations on all clocks hanging from the VPU clock,
    notably the aux UART, making its output unintelligible.

    Fixes: 42de9ad400af ("clk: bcm2835: Add BCM2711_CLOCK_EMMC2 support")
    Reported-by: Nathan Chancellor <natechancellor@gmail.com>
    Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
    Link: https://lore.kernel.org/r/20200730182619.23246-1-nsaenzjulienne@suse.de
    Tested-by: Nathan Chancellor <natechancellor@gmail.com>
    Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
    Signed-off-by: Stephen Boyd <sboyd@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/clk/bcm/clk-bcm2835.c | 25 +++++++++++++++++++++----
    1 file changed, 21 insertions(+), 4 deletions(-)

    diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
    index 6bb7efa12037b..011802f1a6df9 100644
    --- a/drivers/clk/bcm/clk-bcm2835.c
    +++ b/drivers/clk/bcm/clk-bcm2835.c
    @@ -314,6 +314,7 @@ struct bcm2835_cprman {
    struct device *dev;
    void __iomem *regs;
    spinlock_t regs_lock; /* spinlock for all clocks */
    + unsigned int soc;

    /*
    * Real names of cprman clock parents looked up through
    @@ -525,6 +526,20 @@ static int bcm2835_pll_is_on(struct clk_hw *hw)
    A2W_PLL_CTRL_PRST_DISABLE;
    }

    +static u32 bcm2835_pll_get_prediv_mask(struct bcm2835_cprman *cprman,
    + const struct bcm2835_pll_data *data)
    +{
    + /*
    + * On BCM2711 there isn't a pre-divisor available in the PLL feedback
    + * loop. Bits 13:14 of ANA1 (PLLA,PLLB,PLLC,PLLD) have been re-purposed
    + * for to for VCO RANGE bits.
    + */
    + if (cprman->soc & SOC_BCM2711)
    + return 0;
    +
    + return data->ana->fb_prediv_mask;
    +}
    +
    static void bcm2835_pll_choose_ndiv_and_fdiv(unsigned long rate,
    unsigned long parent_rate,
    u32 *ndiv, u32 *fdiv)
    @@ -582,7 +597,7 @@ static unsigned long bcm2835_pll_get_rate(struct clk_hw *hw,
    ndiv = (a2wctrl & A2W_PLL_CTRL_NDIV_MASK) >> A2W_PLL_CTRL_NDIV_SHIFT;
    pdiv = (a2wctrl & A2W_PLL_CTRL_PDIV_MASK) >> A2W_PLL_CTRL_PDIV_SHIFT;
    using_prediv = cprman_read(cprman, data->ana_reg_base + 4) &
    - data->ana->fb_prediv_mask;
    + bcm2835_pll_get_prediv_mask(cprman, data);

    if (using_prediv) {
    ndiv *= 2;
    @@ -665,6 +680,7 @@ static int bcm2835_pll_set_rate(struct clk_hw *hw,
    struct bcm2835_pll *pll = container_of(hw, struct bcm2835_pll, hw);
    struct bcm2835_cprman *cprman = pll->cprman;
    const struct bcm2835_pll_data *data = pll->data;
    + u32 prediv_mask = bcm2835_pll_get_prediv_mask(cprman, data);
    bool was_using_prediv, use_fb_prediv, do_ana_setup_first;
    u32 ndiv, fdiv, a2w_ctl;
    u32 ana[4];
    @@ -682,7 +698,7 @@ static int bcm2835_pll_set_rate(struct clk_hw *hw,
    for (i = 3; i >= 0; i--)
    ana[i] = cprman_read(cprman, data->ana_reg_base + i * 4);

    - was_using_prediv = ana[1] & data->ana->fb_prediv_mask;
    + was_using_prediv = ana[1] & prediv_mask;

    ana[0] &= ~data->ana->mask0;
    ana[0] |= data->ana->set0;
    @@ -692,10 +708,10 @@ static int bcm2835_pll_set_rate(struct clk_hw *hw,
    ana[3] |= data->ana->set3;

    if (was_using_prediv && !use_fb_prediv) {
    - ana[1] &= ~data->ana->fb_prediv_mask;
    + ana[1] &= ~prediv_mask;
    do_ana_setup_first = true;
    } else if (!was_using_prediv && use_fb_prediv) {
    - ana[1] |= data->ana->fb_prediv_mask;
    + ana[1] |= prediv_mask;
    do_ana_setup_first = false;
    } else {
    do_ana_setup_first = true;
    @@ -2238,6 +2254,7 @@ static int bcm2835_clk_probe(struct platform_device *pdev)
    platform_set_drvdata(pdev, cprman);

    cprman->onecell.num = asize;
    + cprman->soc = pdata->soc;
    hws = cprman->onecell.hws;

    for (i = 0; i < asize; i++) {
    --
    2.25.1


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