On 13/09/2019 03:20, Stefan Wahren wrote:
> Am 12.09.19 um 20:52 schrieb Eric Anholt:
>> Matthias Brugger <matthias.bgg@xxxxxxxxx> writes:
>>
>>> On 13/08/2019 18:20, Stefan Wahren wrote:
>>>> The new BCM2711 supports an additional clock for the emmc2 block.
>>>> So add a new compatible and register this clock only for BCM2711.
>>>>
>>>> Signed-off-by: Stefan Wahren <wahrenst@xxxxxxx>
>>>> Reviewed-by: Matthias Brugger <mbrugger@xxxxxxxx>
>>>> Acked-by: Eric Anholt <eric@xxxxxxxxxx>
>>>> ---
>>>> drivers/clk/bcm/clk-bcm2835.c | 20 +++++++++++++++++++-
>>>> 1 file changed, 19 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c
>>>> index 21cd952..fdf672a 100644
>>>> --- a/drivers/clk/bcm/clk-bcm2835.c
>>>> +++ b/drivers/clk/bcm/clk-bcm2835.c
>>>> @@ -114,6 +114,8 @@
>>>> #define CM_AVEODIV 0x1bc
>>>> #define CM_EMMCCTL 0x1c0
>>>> #define CM_EMMCDIV 0x1c4
>>>> +#define CM_EMMC2CTL 0x1d0
>>>> +#define CM_EMMC2DIV 0x1d4
>>>>
>>>> /* General bits for the CM_*CTL regs */
>>>> # define CM_ENABLE BIT(4)
>>>> @@ -290,7 +292,8 @@
>>>> #define BCM2835_MAX_FB_RATE 1750000000u
>>>>
>>>> #define SOC_BCM2835 BIT(0)
>>>> -#define SOC_ALL (SOC_BCM2835)
>>>> +#define SOC_BCM2711 BIT(1)
>>>> +#define SOC_ALL (SOC_BCM2835 | SOC_BCM2711)
>>>>
>>>> /*
>>>> * Names of clocks used within the driver that need to be replaced
>>>> @@ -2003,6 +2006,16 @@ static const struct bcm2835_clk_desc clk_desc_array[] = {
>>>> .frac_bits = 8,
>>>> .tcnt_mux = 39),
>>>>
>>>> + /* EMMC2 clock (only available for BCM2711) */
>>>> + [BCM2711_CLOCK_EMMC2] = REGISTER_PER_CLK(
>>>> + SOC_BCM2711,
>>>> + .name = "emmc2",
>>>> + .ctl_reg = CM_EMMC2CTL,
>>>> + .div_reg = CM_EMMC2DIV,
>>>> + .int_bits = 4,
>>>> + .frac_bits = 8,
>>>> + .tcnt_mux = 42),
>>>> +
>>>> /* General purpose (GPIO) clocks */
>>>> [BCM2835_CLOCK_GP0] = REGISTER_PER_CLK(
>>>> SOC_ALL,
>>>> @@ -2238,8 +2251,13 @@ static const struct cprman_plat_data cprman_bcm2835_plat_data = {
>>>> .soc = SOC_BCM2835,
>>>> };
>>>>
>>>> +static const struct cprman_plat_data cprman_bcm2711_plat_data = {
>>>> + .soc = SOC_BCM2711,
>>>> +};
>>>> +
>>>> static const struct of_device_id bcm2835_clk_of_match[] = {
>>>> { .compatible = "brcm,bcm2835-cprman", .data = &cprman_bcm2835_plat_data },
>>>> + { .compatible = "brcm,bcm2711-cprman", .data = &cprman_bcm2711_plat_data },
>>> Because the RPi4 FW uses bcm2838-cprman as compatible, we will need to add this
>>> here as well.
>> Upstream has not committed to backwards compat with Pi's firmware. That
>> makes the ABI requirement we get held to for upstream's DT absurd, but
>> that's the state of things.
>
> We also learned from past, that's not possible to keep things downstream
> compatible. As soon as a binding is not accepted, this wont work
> anymore. A lot of the downstream stuff is hacky.
>
> For example yesterday, i learned that the thermal node is broken
> (register is part of ring oscillator block). So do we really want to be
> compatible with a hack? I would say: No
>
There is always the possibility to fix this in the FW, which in many cases will
be trivial.
