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Message-ID: <3D3E2940-11E3-4093-8F60-82EB2C11B617@linaro.org>
Date: Wed, 03 Jun 2020 12:52:34 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Amit Singh Tomar <amittomer25@...il.com>, andre.przywara@....com,
vkoul@...nel.org, afaerber@...e.de
CC: dan.j.williams@...el.com, cristian.ciocaltea@...il.com,
dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
linux-actions@...ts.infradead.org
Subject: Re: [PATCH v3 01/10] dmaengine: Actions: get rid of bit fields from dma descriptor
On 2 June 2020 11:03:03 PM IST, Amit Singh Tomar <amittomer25@...il.com> wrote:
>At the moment, Driver uses bit fields to describe registers of the DMA
>descriptor structure that makes it less portable and maintainable, and
>Andre suugested(and even sketched important bits for it) to make use of
>array to describe this DMA descriptors instead. It gives the
>flexibility
>while extending support for other platform such as Actions S700.
>
>This commit removes the "owl_dma_lli_hw" (that includes bit-fields) and
>uses array to describe DMA descriptor.
>
>Suggested-by: Andre Przywara <andre.przywara@....com>
>Signed-off-by: Amit Singh Tomar <amittomer25@...il.com>
>---
>Changes since v2:
> * No change.
>Changes since v1:
> * Defined macro for frame count value.
> * Introduced llc_hw_flen() from patch 2/9.
> * Removed the unnecessary line break.
>Changes since rfc:
> * No change.
>---
>drivers/dma/owl-dma.c | 84
>++++++++++++++++++++++++---------------------------
> 1 file changed, 40 insertions(+), 44 deletions(-)
>
>diff --git a/drivers/dma/owl-dma.c b/drivers/dma/owl-dma.c
>index c683051257fd..dd85c205454e 100644
>--- a/drivers/dma/owl-dma.c
>+++ b/drivers/dma/owl-dma.c
>@@ -120,30 +120,21 @@
> #define BIT_FIELD(val, width, shift, newshift) \
> ((((val) >> (shift)) & ((BIT(width)) - 1)) << (newshift))
>
>-/**
>- * struct owl_dma_lli_hw - Hardware link list for dma transfer
>- * @next_lli: physical address of the next link list
>- * @saddr: source physical address
>- * @daddr: destination physical address
>- * @flen: frame length
>- * @fcnt: frame count
>- * @src_stride: source stride
>- * @dst_stride: destination stride
>- * @ctrla: dma_mode and linklist ctrl config
>- * @ctrlb: interrupt config
>- * @const_num: data for constant fill
>- */
>-struct owl_dma_lli_hw {
>- u32 next_lli;
>- u32 saddr;
>- u32 daddr;
>- u32 flen:20;
>- u32 fcnt:12;
>- u32 src_stride;
>- u32 dst_stride;
>- u32 ctrla;
>- u32 ctrlb;
>- u32 const_num;
>+/* Frame count value is fixed as 1 */
>+#define FCNT_VAL 0x1
>+
>+/* Describe DMA descriptor, hardware link list for dma transfer */
Individual comments for these enums?
>+enum owl_dmadesc_offsets {
>+ OWL_DMADESC_NEXT_LLI = 0,
>+ OWL_DMADESC_SADDR,
>+ OWL_DMADESC_DADDR,
>+ OWL_DMADESC_FLEN,
>+ OWL_DMADESC_SRC_STRIDE,
>+ OWL_DMADESC_DST_STRIDE,
>+ OWL_DMADESC_CTRLA,
>+ OWL_DMADESC_CTRLB,
>+ OWL_DMADESC_CONST_NUM,
>+ OWL_DMADESC_SIZE
> };
>
> /**
>@@ -153,7 +144,7 @@ struct owl_dma_lli_hw {
> * @node: node for txd's lli_list
> */
> struct owl_dma_lli {
>- struct owl_dma_lli_hw hw;
>+ u32 hw[OWL_DMADESC_SIZE];
> dma_addr_t phys;
> struct list_head node;
> };
>@@ -320,6 +311,11 @@ static inline u32 llc_hw_ctrlb(u32 int_ctl)
> return ctl;
> }
>
>+static u32 llc_hw_flen(struct owl_dma_lli *lli)
>+{
>+ return lli->hw[OWL_DMADESC_FLEN] & GENMASK(19, 0);
>+}
>+
> static void owl_dma_free_lli(struct owl_dma *od,
> struct owl_dma_lli *lli)
> {
>@@ -351,8 +347,9 @@ static struct owl_dma_lli *owl_dma_add_lli(struct
>owl_dma_txd *txd,
> list_add_tail(&next->node, &txd->lli_list);
>
> if (prev) {
>- prev->hw.next_lli = next->phys;
>- prev->hw.ctrla |= llc_hw_ctrla(OWL_DMA_MODE_LME, 0);
>+ prev->hw[OWL_DMADESC_NEXT_LLI] = next->phys;
>+ prev->hw[OWL_DMADESC_CTRLA] |=
>+ llc_hw_ctrla(OWL_DMA_MODE_LME, 0);
> }
>
> return next;
>@@ -365,8 +362,7 @@ static inline int owl_dma_cfg_lli(struct
>owl_dma_vchan *vchan,
> struct dma_slave_config *sconfig,
> bool is_cyclic)
> {
>- struct owl_dma_lli_hw *hw = &lli->hw;
>- u32 mode;
>+ u32 mode, ctrlb;
>
> mode = OWL_DMA_MODE_PW(0);
>
>@@ -407,22 +403,22 @@ static inline int owl_dma_cfg_lli(struct
>owl_dma_vchan *vchan,
> return -EINVAL;
> }
>
>- hw->next_lli = 0; /* One link list by default */
>- hw->saddr = src;
>- hw->daddr = dst;
>-
>- hw->fcnt = 1; /* Frame count fixed as 1 */
>- hw->flen = len; /* Max frame length is 1MB */
>- hw->src_stride = 0;
>- hw->dst_stride = 0;
>- hw->ctrla = llc_hw_ctrla(mode,
>- OWL_DMA_LLC_SAV_LOAD_NEXT |
>- OWL_DMA_LLC_DAV_LOAD_NEXT);
>+ lli->hw[OWL_DMADESC_CTRLA] = llc_hw_ctrla(mode,
>+ OWL_DMA_LLC_SAV_LOAD_NEXT |
>+ OWL_DMA_LLC_DAV_LOAD_NEXT);
>
> if (is_cyclic)
>- hw->ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_BLOCK);
>+ ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_BLOCK);
> else
>- hw->ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_SUPER_BLOCK);
>+ ctrlb = llc_hw_ctrlb(OWL_DMA_INTCTL_SUPER_BLOCK);
>+
>+ lli->hw[OWL_DMADESC_NEXT_LLI] = 0;
Again, please preserve the old comments.
>+ lli->hw[OWL_DMADESC_SADDR] = src;
>+ lli->hw[OWL_DMADESC_DADDR] = dst;
>+ lli->hw[OWL_DMADESC_SRC_STRIDE] = 0;
>+ lli->hw[OWL_DMADESC_DST_STRIDE] = 0;
>+ lli->hw[OWL_DMADESC_FLEN] = len | FCNT_VAL << 20;
Please explain what you're doing here.
Thanks,
Mani
>+ lli->hw[OWL_DMADESC_CTRLB] = ctrlb;
>
> return 0;
> }
>@@ -754,7 +750,7 @@ static u32 owl_dma_getbytes_chan(struct
>owl_dma_vchan *vchan)
> /* Start from the next active node */
> if (lli->phys == next_lli_phy) {
> list_for_each_entry(lli, &txd->lli_list, node)
>- bytes += lli->hw.flen;
>+ bytes += llc_hw_flen(lli);
> break;
> }
> }
>@@ -785,7 +781,7 @@ static enum dma_status owl_dma_tx_status(struct
>dma_chan *chan,
> if (vd) {
> txd = to_owl_txd(&vd->tx);
> list_for_each_entry(lli, &txd->lli_list, node)
>- bytes += lli->hw.flen;
>+ bytes += llc_hw_flen(lli);
> } else {
> bytes = owl_dma_getbytes_chan(vchan);
> }
--
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