From: "Wladimir J. van der Laan" <laanwj@gmail.com>
To: Sean Anderson <seanga2@gmail.com>
Cc: Carlos Eduardo de Paula <me@carlosedp.com>,
Anup Patel <Anup.Patel@wdc.com>,
Damien Le Moal <Damien.LeMoal@wdc.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
"linux-riscv@lists.infradead.org"
<linux-riscv@lists.infradead.org>
Subject: Re: [PATCH 08/10] riscv: Add Kendryte K210 device tree
Date: Thu, 20 Feb 2020 11:48:11 +0100 [thread overview]
Message-ID: <20200220104811.eb5goi52qrft74vj@aurora.visucore.com> (raw)
In-Reply-To: <cabd9527-3df3-4e5a-4669-5c14ed44e94d@gmail.com>
> > BTW speaking of which, does anyone know what's up with the K210's DMA
> > controller? It looks like it can only transfer 32-bit values from and to
> > peripherals? At least the kendryte-standalone-sdk goes to great lengths to
> > first allocate a 32-bit buffer then manually copy it to say, bytes or 16-bit
> > words. Seems quite a silly workaround with a lot of overhead.
>
> Do you have a link to that section?
It's not really one section but all over the place in all clients of the DMA.
See for example the SPI here:
https://github.com/kendryte/kendryte-standalone-sdk/blob/develop/lib/drivers/spi.c#L372
Or serial (this one tripped me up):
https://github.com/kendryte/kendryte-standalone-sdk/blob/develop/lib/drivers/uart.c#L265
https://github.com/kendryte/kendryte-standalone-sdk/blob/develop/lib/drivers/uart.c#L163
One can fairly reliably find them by looking for 'malloc' in the drivers.
A few months back I did some experiments with different values for transfer
sizes and such and wasn't able to get the DMA controller to do this, myself.
The "FIX_CACHE" define is new, BTW. They don't DMA directly from/to cached
memory anymore but use an intermediate copy in uncached special I/O memory in
the 4xxxxxxx range. I haven't had problems with e.g. manually DMAing to the screen
through SPI myself but there might be a coherency edge case (their commit messages
are not exactly enlightening).
Kind regards,
Wladimir
next prev parent reply other threads:[~2020-02-20 10:48 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-12 10:34 [PATCH 00/10] Kendryte k210 SoC boards support Damien Le Moal
2020-02-12 10:34 ` [PATCH 01/10] riscv: Fix gitignore Damien Le Moal
2020-02-20 0:15 ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 02/10] riscv: Force flat memory model with no-mmu Damien Le Moal
2020-02-14 20:18 ` Sean Anderson
2020-02-15 2:15 ` Damien Le Moal
2020-02-15 2:26 ` Sean Anderson
2020-02-15 2:40 ` Damien Le Moal
2020-03-02 3:48 ` Anup Patel
2020-03-04 18:38 ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 03/10] riscv: Unaligned load/store handling for M_MODE Damien Le Moal
2020-03-02 3:57 ` Anup Patel
2020-03-04 19:28 ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 04/10] riscv: Add BUILTIN_DTB support Damien Le Moal
2020-03-02 3:58 ` Anup Patel
2020-03-04 19:28 ` Palmer Dabbelt
2020-03-05 4:58 ` Anup Patel
2020-03-05 5:14 ` Damien Le Moal
2020-03-05 5:37 ` Anup Patel
2020-03-05 6:13 ` Damien Le Moal
2020-03-08 6:10 ` Anup Patel
2020-03-05 8:18 ` Atish Patra
2020-03-07 0:02 ` Sean Anderson
2020-03-07 1:51 ` Atish Patra
2020-03-07 2:08 ` Sean Anderson
2020-03-06 23:56 ` Sean Anderson
2020-02-12 10:34 ` [PATCH 05/10] riscv: Add SOC early init support Damien Le Moal
2020-03-04 19:28 ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 06/10] riscv: Add Kendryte K210 SoC support Damien Le Moal
2020-02-14 20:31 ` Sean Anderson
2020-03-04 19:38 ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 07/10] riscv: Select required drivers for Kendryte SOC Damien Le Moal
2020-03-02 3:59 ` Anup Patel
2020-03-04 19:44 ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 08/10] riscv: Add Kendryte K210 device tree Damien Le Moal
2020-02-14 20:51 ` Sean Anderson
2020-02-15 2:34 ` Damien Le Moal
2020-02-15 2:48 ` Sean Anderson
2020-02-15 3:00 ` Damien Le Moal
2020-02-18 14:12 ` Carlos Eduardo de Paula
2020-02-18 14:18 ` Sean Anderson
2020-02-18 14:30 ` Carlos Eduardo de Paula
2020-02-18 17:48 ` Sean Anderson
2020-02-18 19:26 ` Carlos Eduardo de Paula
2020-02-19 9:06 ` Wladimir J. van der Laan
2020-02-19 22:28 ` Sean Anderson
2020-02-20 10:48 ` Wladimir J. van der Laan [this message]
2020-02-22 19:07 ` Wladimir J. van der Laan
2020-04-01 17:55 ` Drew Fustini
2020-04-02 2:24 ` Damien Le Moal
2020-02-19 8:50 ` Wladimir J. van der Laan
2020-02-27 19:43 ` Sean Anderson
2020-03-02 4:06 ` Anup Patel
2020-03-02 4:15 ` Damien Le Moal
2020-03-02 4:22 ` Anup Patel
2020-03-02 4:51 ` Damien Le Moal
2020-03-02 5:05 ` Anup Patel
2020-03-02 5:08 ` Damien Le Moal
2020-03-07 0:18 ` Sean Anderson
2020-03-07 4:11 ` Anup Patel
2020-03-04 19:44 ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 09/10] riscv: Kendryte K210 default config Damien Le Moal
2020-03-02 4:07 ` Anup Patel
2020-03-04 19:44 ` Palmer Dabbelt
2020-02-12 10:34 ` [PATCH 10/10] riscv: create a loader.bin for the kendryte kflash.py tool Damien Le Moal
2020-03-02 4:08 ` Anup Patel
2020-03-04 19:44 ` Palmer Dabbelt
2020-02-14 15:05 ` [PATCH 00/10] Kendryte k210 SoC boards support Carlos Eduardo de Paula
2020-02-15 2:02 ` Damien Le Moal
2020-02-17 13:28 ` Carlos Eduardo de Paula
2020-02-26 21:31 ` Carlos Eduardo de Paula
2020-02-27 2:18 ` Damien Le Moal
2020-02-28 20:32 ` Sean Anderson
2020-03-02 3:01 ` Damien Le Moal
2020-03-02 3:53 ` Sean Anderson
2020-03-02 4:11 ` Damien Le Moal
2020-03-02 4:18 ` Sean Anderson
2020-03-02 4:54 ` Damien Le Moal
2020-03-02 4:56 ` Sean Anderson
2020-03-02 5:03 ` Damien Le Moal
2020-03-02 4:17 ` Anup Patel
2020-03-02 4:21 ` Sean Anderson
2020-03-02 4:48 ` Damien Le Moal
2020-03-02 4:51 ` Damien Le Moal
2020-03-02 5:02 ` Sean Anderson
2020-03-02 5:11 ` Damien Le Moal
2020-03-02 5:25 ` Sean Anderson
2020-03-02 5:43 ` Damien Le Moal
2020-03-04 19:44 ` Palmer Dabbelt
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