linux-kernel - Re: [PATCH v2 2/2] firmware: add exynos acpm driver

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Message-ID: <1e76bc70-21a6-4ac7-99ea-30a7ccf387bb@kernel.org>
Date: Wed, 23 Oct 2024 11:00:04 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Tudor Ambarus <tudor.ambarus@...aro.org>, jassisinghbrar@...il.com
Cc: alim.akhtar@...sung.com, mst@...hat.com, javierm@...hat.com,
 tzimmermann@...e.de, bartosz.golaszewski@...aro.org,
 luzmaximilian@...il.com, sudeep.holla@....com, conor.dooley@...rochip.com,
 bjorn@...osinc.com, ulf.hansson@...aro.org,
 linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, marcan@...can.st, neal@...pa.dev,
 alyssa@...enzweig.io, broonie@...nel.org, andre.draszik@...aro.org,
 willmcvicker@...gle.com, peter.griffin@...aro.org, kernel-team@...roid.com,
 vincent.guittot@...aro.org, daniel.lezcano@...aro.org
Subject: Re: [PATCH v2 2/2] firmware: add exynos acpm driver

On 22/10/2024 09:58, Tudor Ambarus wrote:
> 
>>>>
>>>> I also cannot find any piece of code setting several of above, e.g. tx_base
>>>
>>> I'm not writing any SRAM configuration fields, these fields are used to
>>> read/retrive the channel parameters from SRAM.
>>
>> I meany tx_base is always 0. Where is this property set? Ever?
> 
> It's not zero. My assumption is it is set in the acpm firmware, but I

Where is any assignment to this member?


> don't have access to that to verify. Here are some debug prints made in
> the linux driver:
> 
> [    0.069575][    T1] gs-acpm-ipc 17610000.mailbox:
> exynos_mbox_chan_init ID = 2 poll = 1, mlen = 16, qlen = 5
> [    0.069927][    T1] gs-acpm-ipc 17610000.mailbox:
> exynos_mbox_chan_init ID = 2 offsets: rx_base = 0x00038290 rx_front =
> 0x0003828c, rx_rear = 0x00038288
> [    0.070449][    T1] gs-acpm-ipc 17610000.mailbox:
> exynos_mbox_chan_init ID = 2 offsets: tx_base = 0x000382f0 tx_front =
> 0x000382ec, tx_rear = 0x000382e8
> 
> 
> tx_base contains the SRAM offset of the RX queue used in linux. The
> offset is relative to the base address of the SRAM config data.
> 
> tx_base is seen/named from the firmware's point of view, thus named TX.
> I assume the same struct is defined in the acpm firmware.
> 
> 
> Somewhere below in the linux driver I get the RX ring base address by doing:
> 
> rx->base = exynos_acpm_get_iomem_addr(base, &shmem_chan->tx_base);

tx_base is still 0.

> 
> where base is the SRAM base address of the channels configuration data.
> 
> static void __iomem *exynos_acpm_get_iomem_addr(void __iomem *base,
> 
> 
>                                                 void __iomem *addr)
> 
> 
> {
> 
> 
>         u32 offset;
> 
> 
> 
> 
> 
>         offset = readl_relaxed(addr);
> 
> 
>         return base + offset;
> 
> 
> }
> 
> Hope this clarifies a bit these struct members.

No, where is tx_base assigned?

Best regards,
Krzysztof