linux-kernel - Re: [PATCH v4 2/2] dmaengine: tegra210-adma: check for adma max page

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Message-ID: <84c4c672-fc17-4f75-b3ce-388b987d32ab@nvidia.com>
Date: Wed, 5 Feb 2025 18:28:34 +0530
From: Mohan Kumar D <mkumard@...dia.com>
To: Jon Hunter <jonathanh@...dia.com>, vkoul@...nel.org,
 thierry.reding@...il.com
Cc: dmaengine@...r.kernel.org, linux-tegra@...r.kernel.org,
 linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: [PATCH v4 2/2] dmaengine: tegra210-adma: check for adma max page


On 05-02-2025 17:10, Jon Hunter wrote:
>
>
> On 05/02/2025 03:31, Mohan Kumar D wrote:
>> Have additional check for max channel page during the probe
>> to cover if any offset overshoot happens due to wrong DT
>> configuration.
>>
>> Fixes: 68811c928f88 ("dmaengine: tegra210-adma: Support channel page")
>> Cc: stable@...r.kernel.org
>> Signed-off-by: Mohan Kumar D <mkumard@...dia.com>
>> ---
>>   drivers/dma/tegra210-adma.c | 7 ++++++-
>>   1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/dma/tegra210-adma.c b/drivers/dma/tegra210-adma.c
>> index a0bd4822ed80..801740ad8e0d 100644
>> --- a/drivers/dma/tegra210-adma.c
>> +++ b/drivers/dma/tegra210-adma.c
>> @@ -83,7 +83,9 @@ struct tegra_adma;
>>    * @nr_channels: Number of DMA channels available.
>>    * @ch_fifo_size_mask: Mask for FIFO size field.
>>    * @sreq_index_offset: Slave channel index offset.
>> + * @max_page: Maximum ADMA Channel Page.
>>    * @has_outstanding_reqs: If DMA channel can have outstanding 
>> requests.
>> + * @set_global_pg_config: Global page programming.
>>    */
>>   struct tegra_adma_chip_data {
>>       unsigned int (*adma_get_burst_config)(unsigned int burst_size);
>> @@ -99,6 +101,7 @@ struct tegra_adma_chip_data {
>>       unsigned int nr_channels;
>>       unsigned int ch_fifo_size_mask;
>>       unsigned int sreq_index_offset;
>> +    unsigned int max_page;
>>       bool has_outstanding_reqs;
>>       void (*set_global_pg_config)(struct tegra_adma *tdma);
>>   };
>> @@ -854,6 +857,7 @@ static const struct tegra_adma_chip_data 
>> tegra210_chip_data = {
>>       .nr_channels        = 22,
>>       .ch_fifo_size_mask    = 0xf,
>>       .sreq_index_offset    = 2,
>> +    .max_page        = 0,
>>       .has_outstanding_reqs    = false,
>>       .set_global_pg_config    = NULL,
>>   };
>> @@ -871,6 +875,7 @@ static const struct tegra_adma_chip_data 
>> tegra186_chip_data = {
>>       .nr_channels        = 32,
>>       .ch_fifo_size_mask    = 0x1f,
>>       .sreq_index_offset    = 4,
>> +    .max_page        = 4,
>>       .has_outstanding_reqs    = true,
>>       .set_global_pg_config    = tegra186_adma_global_page_config,
>>   };
>> @@ -921,7 +926,7 @@ static int tegra_adma_probe(struct 
>> platform_device *pdev)
>>               page_offset = res_page->start - res_base->start;
>>               page_no = div_u64(page_offset, cdata->ch_base_offset);
>>   -            if (WARN_ON(page_no == 0))
>> +            if (WARN_ON(page_no == 0 || page_no > cdata->max_page))
>
> So no one should ever specify the 'page' region for Tegra210, correct? 
> If they did then this would always fail. I don't know if it is also 
> worth checking if someone has a 'page' region for a device that has 
> max_page == 0?
Yes, DT binding specifies "page" should not be used for Tegra210 and 
above conditions takes care. I believe above condition should suffice.
>
> Jon