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From: Florian Fainelli <f.fainelli@gmail.com>
To: Matthias Brugger <matthias.bgg@gmail.com>,
	Stefan Wahren <wahrenst@gmx.net>, Eric Anholt <eric@anholt.net>,
	Ray Jui <rjui@broadcom.com>,
	Scott Branden <sbranden@broadcom.com>,
	Wolfram Sang <wsa@the-dreams.de>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Michael Turquette <mturquette@baylibre.com>,
	Stephen Boyd <sboyd@kernel.org>
Cc: devicetree@vger.kernel.org,
	bcm-kernel-feedback-list@broadcom.com, linux-i2c@vger.kernel.org,
	linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-rpi-kernel@lists.infradead.org
Subject: Re: [PATCH V2 05/13] clk: bcm2835: Add BCM2711_CLOCK_EMMC2 support
Date: Fri, 13 Sep 2019 16:02:19 -0700
Message-ID: <e75d8d6e-8f63-09b7-2489-dc87bc9dcd98@gmail.com> (raw)
In-Reply-To: <218baa70-9849-63db-4989-c6d658b11c6d@gmail.com>

On 9/13/19 12:13 AM, Matthias Brugger wrote:
> 
> 
> On 13/09/2019 03:20, Stefan Wahren wrote:
>> Am 12.09.19 um 20:52 schrieb Eric Anholt:
>>> Matthias Brugger <matthias.bgg@gmail.com> 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@gmx.net>
>>>>> Reviewed-by: Matthias Brugger <mbrugger@suse.com>
>>>>> Acked-by: Eric Anholt <eric@anholt.net>
>>>>> ---
>>>>>  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.

In many cases, the firmware can certainly be changed to support both
downstream and upstream properties, as long as the layout is not
fundamentally incompatible obviously. If this is just a game of
compatible strings, both can be provided and it should not cause any
issues as long as you are not mixing downstream and upstream drivers for
the same purpose.
-- 
Florian

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Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-13 16:20 [PATCH V2 00/13] ARM: Add minimal Raspberry Pi 4 support Stefan Wahren
2019-08-13 16:20 ` [PATCH V2 01/13] ARM: dts: bcm283x: Enable HDMI at board level Stefan Wahren
2019-08-13 16:20 ` [PATCH V2 02/13] ARM: dts: bcm283x: Move BCM2835/6/7 specific to bcm2835-common.dtsi Stefan Wahren
2019-08-13 16:20 ` [PATCH V2 03/13] dt-bindings: bcm2835-cprman: Add bcm2711 support Stefan Wahren
2019-08-16 17:41   ` Stephen Boyd
2019-08-27 16:00   ` Rob Herring
2019-08-13 16:20 ` [PATCH V2 04/13] clk: bcm2835: Introduce SoC specific clock registration Stefan Wahren
2019-08-13 16:20 ` [PATCH V2 05/13] clk: bcm2835: Add BCM2711_CLOCK_EMMC2 support Stefan Wahren
2019-09-12 17:24   ` Matthias Brugger
2019-09-12 18:52     ` Eric Anholt
2019-09-13  1:20       ` Stefan Wahren
2019-09-13  7:13         ` Matthias Brugger
2019-09-13 23:02           ` Florian Fainelli [this message]
2019-08-13 16:20 ` [PATCH V2 06/13] clk: bcm2835: Mark PLLD_PER as CRITICAL Stefan Wahren
2019-08-16 17:39   ` Stephen Boyd
2019-08-13 16:20 ` [PATCH V2 07/13] dt-bindings: i2c: bcm2835: Add brcm, bcm2711 compatible Stefan Wahren
2019-08-27 16:00   ` [PATCH V2 07/13] dt-bindings: i2c: bcm2835: Add brcm,bcm2711 compatible Rob Herring
2019-08-13 16:20 ` [PATCH V2 08/13] i2c: bcm2835: Avoid clk stretch quirk for BCM2711 Stefan Wahren
2019-08-14 19:36   ` Wolfram Sang
2019-08-17  7:32     ` Stefan Wahren
2019-08-17  8:30       ` Wolfram Sang
2019-08-13 16:20 ` [PATCH V2 09/13] dt-bindings: arm: Convert BCM2835 board/soc bindings to json-schema Stefan Wahren
2019-08-13 17:22   ` Rob Herring
2019-08-14 19:21     ` Stefan Wahren
2019-08-14 23:06       ` Rob Herring
2019-08-13 16:20 ` [PATCH V2 10/13] dt-bindings: arm: bcm2835: Add Raspberry Pi 4 to DT schema Stefan Wahren
2019-08-13 16:20 ` [PATCH V2 11/13] ARM: bcm: Add support for BCM2711 SoC Stefan Wahren
2019-09-10 14:13   ` Matthias Brugger
2019-08-13 16:20 ` [PATCH V2 12/13] ARM: dts: Add minimal Raspberry Pi 4 support Stefan Wahren
2019-08-13 16:20 ` [PATCH V2 13/13] MAINTAINERS: Add BCM2711 to BCM2835 ARCH Stefan Wahren
2019-08-13 20:42 ` [PATCH V2 00/13] ARM: Add minimal Raspberry Pi 4 support Eric Anholt

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