Linux SPI subsystem development
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From: Alex Elder <elder@riscstar.com>
To: Yixun Lan <dlan@gentoo.org>
Cc: broonie@kernel.org, robh@kernel.org, krzk+dt@kernel.org,
	conor+dt@kernel.org, linux-spi@vger.kernel.org,
	devicetree@vger.kernel.org, paul.walmsley@sifive.com,
	palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr,
	p.zabel@pengutronix.de, spacemit@lists.linux.dev,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3] spi: spacemit: introduce SpacemiT K1 SPI controller driver
Date: Thu, 18 Sep 2025 09:47:28 -0500	[thread overview]
Message-ID: <cedaad98-1eba-431f-af4a-b84e106e5f65@riscstar.com> (raw)
In-Reply-To: <20250918143928-GYB1274501@gentoo.org>

On 9/18/25 9:39 AM, Yixun Lan wrote:
>>>> +	u32 data_reg_addr;		/* DMA address of the data register */
>>> s/data_reg_addr/ssp_data/? I just feel uncomfortable with redundant 'reg_addr'
>> My convention is normally "virt" or maybe "base" to represent
>> a virtual address, and "addr" to represent I/O addresses.
>>
>> This symbol represents the physical address that underlies the
>> "SSP Data Register", which fills the TX FIFO when written and
>> drains the RX FIFO when read.
>>
>> How about "data_addr"?  I know you wouldn't like "reg_addr".
>>
> another idea here, instead of introducing a variable here,
> how about simply using plain iores->start + SSP_DATAR?
> 
> so you can cache "iores" instead..

This code has gone through a huge amount of refactoring.

I hadn't looked, but now I see this field is used exactly one
place in the code, in k1_spi_prepare_dma_io().  It's still
needed though.

Here's what I plan to do.  Rather than saving data_reg_addr,
I will simply save base_addr, which is the I/O resource start
address that corresponds to the mapped virtual pointer, "base".

Then in k1_spi_prepare_dma_io() I'll use base_addr + SSP_DATAR.

OK?

					-Alex


  reply	other threads:[~2025-09-18 14:47 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-09-17 22:07 [PATCH 0/3] spi: support the SpacemiT K1 SPI controller Alex Elder
2025-09-17 22:07 ` [PATCH 1/3] dt-bindings: spi: add SpacemiT K1 SPI support Alex Elder
2025-09-17 23:15   ` Yixun Lan
2025-09-17 23:40     ` Alex Elder
2025-09-18  0:16       ` Yixun Lan
2025-09-18  2:59         ` Alex Elder
2025-09-18  7:43           ` Troy Mitchell
2025-09-18 12:00             ` Alex Elder
2025-09-18 19:57       ` Rob Herring
2025-09-18 20:02         ` Alex Elder
2025-10-06  8:10   ` Krzysztof Kozlowski
2025-09-17 22:07 ` [PATCH 2/3] spi: spacemit: introduce SpacemiT K1 SPI controller driver Alex Elder
2025-09-18  7:47   ` Troy Mitchell
2025-09-18 12:00     ` Alex Elder
2025-09-18 12:41   ` Yixun Lan
2025-09-18 13:45     ` Alex Elder
2025-09-18 14:39       ` Yixun Lan
2025-09-18 14:47         ` Alex Elder [this message]
2025-09-18 14:56           ` Yixun Lan
2025-09-18 15:44         ` Alex Elder
2025-09-18 15:58         ` Alex Elder
2025-09-18 16:22         ` Alex Elder
2025-09-17 22:07 ` [PATCH 3/3] riscv: dts: spacemit: define a SPI controller node Alex Elder
2025-09-18 13:32   ` Yixun Lan
2025-09-18 13:51     ` Alex Elder
2025-09-18 14:06       ` Yixun Lan
2025-09-18 14:20         ` Alex Elder
2025-09-18 15:04           ` Yixun Lan
2025-09-18 14:33     ` Yao Zi
2025-09-18 16:22       ` Alex Elder
2025-09-19 15:25         ` Alex Elder

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