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[213.161.3.76]) by smtp.gmail.com with ESMTPSA id bt28-20020a056000081c00b0020fcc655e4asm14349200wrb.5.2022.06.20.21.12.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 20 Jun 2022 21:12:59 -0700 (PDT) From: Jernej =?utf-8?B?xaBrcmFiZWM=?= To: Chen-Yu Tsai , Vinod Koul , Samuel Holland Cc: dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev Subject: Re: Re: [PATCH] dmaengine: sun6i: Set the maximum segment size Date: Tue, 21 Jun 2022 06:12:53 +0200 Message-ID: <1793109.atdPhlSkOF@kista> In-Reply-To: References: <20220617034209.57337-1-samuel@sholland.org> <3494277.R56niFO833@kista> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: dmaengine@vger.kernel.org Dne torek, 21. junij 2022 ob 02:20:11 CEST je Samuel Holland napisal(a): > Hi Jernej, >=20 > On 6/20/22 1:28 PM, Jernej =C5=A0krabec wrote: > > Dne petek, 17. junij 2022 ob 05:42:09 CEST je Samuel Holland napisal(a): > >> The sun6i DMA engine supports segment sizes up to 2^25-1 bytes. This is > >> explicitly stated in newer SoC documentation (H6, D1), and it is impli= ed > >> in older documentation by the 25-bit width of the "bytes left in the > >> current segment" register field. > >=20 > > At least A10 user manual says 128k max in description for Byte Counter= =20 > > register (0x100+N*0x20+0xC), although field size is defined as 23:0, bu= t=20 that's=20 > > still less than 2^25-1. A20 supports only 128k too according to manual.= =20 New=20 > > quirk should be introduced for this. >=20 > Thanks for checking this. A10 and A20 use a separate driver (sun4i-dma).= =20 That > driver will also benefit from setting the max segment size, so I will sen= d a > patch for it. >=20 > I think all of the variants supported by sun6i-dma have the same segment= =20 size > capability, so no quirk is needed here. Ah, yes. Then this patch is: Reviewed-by: Jernej Skrabec Best regards, Jernej >=20 > Regards, > Samuel >=20 > >> > >> Exposing the real segment size limit (instead of the 64k default) > >> reduces the number of SG list segments needed for a transaction. > >> > >> Signed-off-by: Samuel Holland > >> --- > >> Tested on A64, verified that the maximum ALSA PCM period increased, and > >> that audio playback still worked. > >> > >> drivers/dma/sun6i-dma.c | 3 +++ > >> 1 file changed, 3 insertions(+) > >> > >> diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c > >> index b7557f437936..1425f87d97b7 100644 > >> --- a/drivers/dma/sun6i-dma.c > >> +++ b/drivers/dma/sun6i-dma.c > >> @@ -9,6 +9,7 @@ > >> =20 > >> #include > >> #include > >> +#include > >> #include > >> #include > >> #include > >> @@ -1334,6 +1335,8 @@ static int sun6i_dma_probe(struct platform_devic= e=20 > > *pdev) > >> INIT_LIST_HEAD(&sdc->pending); > >> spin_lock_init(&sdc->lock); > >> =20 > >> + dma_set_max_seg_size(&pdev->dev, DMA_BIT_MASK(25)); > >> + > >> dma_cap_set(DMA_PRIVATE, sdc->slave.cap_mask); > >> dma_cap_set(DMA_MEMCPY, sdc->slave.cap_mask); > >> dma_cap_set(DMA_SLAVE, sdc->slave.cap_mask); > >> --=20 > >> 2.35.1 > >> > >> > >=20 > >=20 >=20 >=20