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Message-ID: <6a157604-16dd-43b2-90aa-466e8185ff53@linaro.org>
Date: Fri, 26 Jan 2024 07:27:00 +0000
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Subject: Re: [PATCH v2 21/28] spi: s3c64xx: infer fifosize from the compatible
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To: Sam Protsenko <semen.protsenko@linaro.org>
Cc: broonie@kernel.org, andi.shyti@kernel.org, arnd@arndb.de,
 robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org, conor+dt@kernel.org,
 alim.akhtar@samsung.com, linux-spi@vger.kernel.org,
 linux-samsung-soc@vger.kernel.org, devicetree@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
 linux-arch@vger.kernel.org, andre.draszik@linaro.org,
 peter.griffin@linaro.org, kernel-team@android.com, willmcvicker@google.com
References: <20240125145007.748295-1-tudor.ambarus@linaro.org>
 <20240125145007.748295-22-tudor.ambarus@linaro.org>
 <CAPLW+4mG_xVvZRrE_jfMxK2zO9GnLAPrHPdzW5bCOPpoiuCjsA@mail.gmail.com>
From: Tudor Ambarus <tudor.ambarus@linaro.org>
In-Reply-To: <CAPLW+4mG_xVvZRrE_jfMxK2zO9GnLAPrHPdzW5bCOPpoiuCjsA@mail.gmail.com>
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On 1/25/24 22:28, Sam Protsenko wrote:
> On Thu, Jan 25, 2024 at 8:50 AM Tudor Ambarus <tudor.ambarus@linaro.org> wrote:
>> Infer the FIFO size from the compatible, where all the instances of the
>> SPI IP have the same FIFO size. This way we no longer depend on the SPI
>> alias from the device tree to select the FIFO size, thus we remove the
>> dependency of the driver on the SPI alias.
>>
>> Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
>> ---
>>  drivers/spi/spi-s3c64xx.c | 8 ++++----
>>  1 file changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
>> index 5a93ed4125b0..b86eb0a77b60 100644
>> --- a/drivers/spi/spi-s3c64xx.c
>> +++ b/drivers/spi/spi-s3c64xx.c
>> @@ -1381,7 +1381,7 @@ static const struct dev_pm_ops s3c64xx_spi_pm = {
>>  };
>>
>>  static const struct s3c64xx_spi_port_config s3c2443_spi_port_config = {
>> -       .fifo_lvl_mask  = { 0x7f },
> How will it work with already existing out-of-tree dts's, if only
> kernel image gets updated? I wonder if it's considered ok to break
> that compatibility like this.
> 

ah, good catch, Sam! I prepared everything to not break older device
trees and then I removed this :).

>> +       .fifosize       = 64,

Adding .fifosize and keeping fifo_lvl_mask will not break backward
compatibility. In s3c64xx_spi_get_fifosize() I first check if .fifosize
is set and use that, and if not set, use the .fifo_lvl_mask.