Thanks Lucas. Let's wait for comments from Vinod.
-----Original Message-----
From: Lucas Stach [mailto:l.st...@pengutronix.de]
Sent: 2018年6月26日 23:04
To: Robin Gong <yibin.g...@nxp.com>; vk...@kernel.org; s.ha...@pengutronix.de;
dan.j.willi...@intel.com; gre...@linuxfoundation.org; jsl...@suse.com
Cc: linux-ser...@vger.kernel.org; dmaeng...@vger.kernel.org;
linux-kernel@vger.kernel.org; linux-arm-ker...@lists.infradead.org;
dl-linux-imx <linux-...@nxp.com>
Subject: Re: [PATCH v5 0/7] add virt-dma support for imx-sdma
Hi Robin,
I've tested this whole series with the SDMA being used for SPI, UART and SSI
with no regressions spotted. As this should cover most common use-cases, I
think this series is good to go in.
Tested-by: Lucas Stach <l.st...@pengutronix.de>
Regards,
Lucas
Am Mittwoch, den 20.06.2018, 00:56 +0800 schrieb Robin Gong:
> The legacy sdma driver has below limitations or drawbacks:
> 1. Hardcode the max BDs number as "PAGE_SIZE / sizeof(*)", and alloc
> one page size for one channel regardless of only few BDs needed
> most time. But in few cases, the max PAGE_SIZE maybe not enough.
> 2. One SDMA channel can't stop immediatley once channel disabled
> which
> means SDMA interrupt may come in after this channel
> terminated.There
> are some patches for this corner case such as commit
> "2746e2c389f9",
> but not cover non-cyclic.
>
> The common virt-dma overcomes the above limitations. It can alloc bd
> dynamically and free bd once this tx transfer done. No memory wasted
> or maximum limititation here, only depends on how many memory can be
> requested from kernel. For No.2, such issue can be workaround by
> checking if there is available descript("sdmac->desc") now once the
> unwanted interrupt coming. At last the common virt-dma is easier for sdma
> driver maintain.
>
> Change from v4:
> 1. identify lockdep issue which caused by allocate memory with
> 'GFP_KERNEL', change to 'GFP_NOWAIT' instead so that lockdep
> ignore check. That also make sense since Audio/uart driver may
> call dma function after spin_lock_irqsave()...
> 2. use dma pool instead for bd description allocated,since audio
> driver may call dma_terminate_all in irq. Please refer to 7/7.
> 3. remove 7/7 serial patch in v4, since lockdep issued fixed by No.1
>
> Change from v3:
> 1. add two uart patches which impacted by this patchset.
> 2. unlock 'vc.lock' before cyclic dma callback and lock again after
> it because some driver such as uart will call dmaengine_tx_status
> which will acquire 'vc.lock' again and dead lock comes out.
> 3. remove 'Revert commit' stuff since that patch is not wrong and
> combine two patch into one patch as Sascha's comment.
>
> Change from v2:
> 1. include Sascha's patch to make the main patch easier to review.
> Thanks Sacha.
> 2. remove useless 'desc'/'chan' in struct sdma_channe.
>
> Change from v1:
> 1. split v1 patch into 5 patches.
> 2. remove some unnecessary condition check.
> 3. remove unnecessary 'pending' list.
>
> Robin Gong (6):
> tty: serial: imx: correct dma cookie status
> dmaengine: imx-sdma: add virt-dma support
> dmaengine: imx-sdma: remove useless 'lock' and 'enabled' in 'struct
> sdma_channel'
> dmaengine: imx-sdma: remove the maximum limitation for bd numbers
> dmaengine: imx-sdma: add sdma_transfer_init to decrease code overlap
> dmaengine: imx-sdma: alloclate bd memory from dma pool
>
> Sascha Hauer (1):
> dmaengine: imx-sdma: factor out a struct sdma_desc from struct
> sdma_channel
>
> drivers/dma/Kconfig | 1 +
> drivers/dma/imx-sdma.c | 400
> +++++++++++++++++++++++++++--------------------
> drivers/tty/serial/imx.c | 2 +-
> 3 files changed, 235 insertions(+), 168 deletions(-)
>
