[PATCH] nvme-apple: fix DMA-API warning

[Sven Peter]

On Wed, Oct 12, 2022, at 13:46, Russell King (Oracle) wrote:
> Fix the following DMA-API warning:

Thanks for fixing this!

I'd probably use something like "Communicate unlimited segment size support to DMA mapping code"
as the title since that's the actual change which then happens to fix the warning and
maybe also mention that this is done in pci.c and was dropped by mistake when
apple.c was forked from there.

This could also use a Fixes tag to reference the commit that introduced this driver.

With those things addressed,

Reviewed-by: Sven Peter <sven at svenpeter.dev>


Thanks,


Sven


>
> DMA-API: nvme-apple 27bcc0000.nvme: mapping sg segment longer than 
> device claims to support [len=69632] [max=65536]
> WARNING: CPU: 3 PID: 1 at kernel/dma/debug.c:1160 
> debug_dma_map_sg+0x310/0x3a0
> Modules linked in: tps6598x roles typec rtc_macsmc gpio_macsmc 
> nvme_apple apple_mailbox apple_sart pcie_apple macsmc_rtkit macsmc 
> pinctrl_apple_gpio i2c_apple
> CPU: 3 PID: 1 Comm: init Not tainted 6.0.0+ #1081
> Hardware name: Apple Mac mini (M1, 2020) (DT)
> pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : debug_dma_map_sg+0x310/0x3a0
> lr : debug_dma_map_sg+0x310/0x3a0
> ...
> Call trace:
>  debug_dma_map_sg+0x310/0x3a0
>  __dma_map_sg_attrs+0x98/0xf4
>  dma_map_sg_attrs+0xc/0x1c
>  apple_nvme_queue_rq+0x218/0x67c [nvme_apple]
>  blk_mq_dispatch_rq_list+0x198/0x81c
>  blk_mq_do_dispatch_sched+0x2b0/0x340
>  __blk_mq_sched_dispatch_requests+0x104/0x154
>  blk_mq_sched_dispatch_requests+0x38/0x70
>  __blk_mq_run_hw_queue+0x80/0x130
>  __blk_mq_delay_run_hw_queue+0x84/0x90
>  blk_mq_run_hw_queue+0x134/0x170
>  blk_mq_sched_insert_requests+0xec/0x300
>  blk_mq_flush_plug_list+0x104/0x430
>  __blk_flush_plug+0xe8/0x130
>  blk_finish_plug+0x30/0x1f0
>  read_pages+0x1ec/0x334
>  page_cache_ra_unbounded+0x158/0x1bc
>  page_cache_ra_order+0x80/0x2c0
>  filemap_fault+0x4bc/0x970
>  __do_fault+0x38/0x144
>  __handle_mm_fault+0x7c4/0xc60
>  handle_mm_fault+0x120/0x2a0
>  do_page_fault+0x130/0x47c
>  do_translation_fault+0xa0/0xb0
>  do_mem_abort+0x40/0x90
>  el0_da+0x2c/0x80
>  el0t_64_sync_handler+0x60/0xb4
>  el0t_64_sync+0x168/0x16c
> ---[ end trace 0000000000000000 ]---
>
> Suggested-by: Sven Peter <sven at svenpeter.dev>
> Signed-off-by: Russell King (Oracle) <rmk+kernel at armlinux.org.uk>
> ---
>  drivers/nvme/host/apple.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/nvme/host/apple.c b/drivers/nvme/host/apple.c
> index 5fc5ea196b40..ff8b083dc5c6 100644
> --- a/drivers/nvme/host/apple.c
> +++ b/drivers/nvme/host/apple.c
> @@ -1039,6 +1039,8 @@ static void apple_nvme_reset_work(struct 
> work_struct *work)
>  					 dma_max_mapping_size(anv->dev) >> 9);
>  	anv->ctrl.max_segments = NVME_MAX_SEGS;
> 
> +	dma_set_max_seg_size(anv->dev, 0xffffffff);
> +
>  	/*
>  	 * Enable NVMMU and linear submission queues.
>  	 * While we could keep those disabled and pretend this is slightly
> -- 
> 2.30.2