From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A3C12C77B7E for ; Sun, 28 May 2023 19:48:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231377AbjE1Ts5 (ORCPT ); Sun, 28 May 2023 15:48:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34862 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231393AbjE1Tsz (ORCPT ); Sun, 28 May 2023 15:48:55 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E4F1CE1 for ; Sun, 28 May 2023 12:48:52 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7705E62004 for ; Sun, 28 May 2023 19:48:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 94AC8C433EF; Sun, 28 May 2023 19:48:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1685303331; bh=MPUKUD3Ude5txd15bwOm4zTWDhjg7NyNOPaZ35ze0Qg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L2okzRWz5/iqAYgxA9xJzdgrOs1tocczhMwk1PSqso6Ez/ymWeodVf4m0+CqpsAUV Rg5REl5KGK8BSJYwPhr+5XC8tFkojEaqBLsD7FKClw10U1q/h/d6nDcvArxc12dFae mGY4x8wBv7OM/j84P6JmC836jv1XSbLBA1t1sqHw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Christophe Leroy , Mark Brown Subject: [PATCH 5.15 08/69] spi: fsl-cpm: Use 16 bit mode for large transfers with even size Date: Sun, 28 May 2023 20:11:28 +0100 Message-Id: <20230528190828.656041914@linuxfoundation.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230528190828.358612414@linuxfoundation.org> References: <20230528190828.358612414@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Christophe Leroy (cherry picked from upstream fc96ec826bced75cc6b9c07a4ac44bbf651337ab) On CPM, the RISC core is a lot more efficiant when doing transfers in 16-bits chunks than in 8-bits chunks, but unfortunately the words need to be byte swapped as seen in a previous commit. So, for large tranfers with an even size, allocate a temporary tx buffer and byte-swap data before and after transfer. This change allows setting higher speed for transfer. For instance on an MPC 8xx (CPM1 comms RISC processor), the documentation tells that transfer in byte mode at 1 kbit/s uses 0.200% of CPM load at 25 MHz while a word transfer at the same speed uses 0.032% of CPM load. This means the speed can be 6 times higher in word mode for the same CPM load. For the time being, only do it on CPM1 as there must be a trade-off between the CPM load reduction and the CPU load required to byte swap the data. Signed-off-by: Christophe Leroy Link: https://lore.kernel.org/r/f2e981f20f92dd28983c3949702a09248c23845c.1680371809.git.christophe.leroy@csgroup.eu Signed-off-by: Mark Brown Signed-off-by: Greg Kroah-Hartman --- drivers/spi/spi-fsl-cpm.c | 23 +++++++++++++++++++++++ drivers/spi/spi-fsl-spi.c | 3 +++ 2 files changed, 26 insertions(+) --- a/drivers/spi/spi-fsl-cpm.c +++ b/drivers/spi/spi-fsl-cpm.c @@ -21,6 +21,7 @@ #include #include #include +#include #include "spi-fsl-cpm.h" #include "spi-fsl-lib.h" @@ -120,6 +121,21 @@ int fsl_spi_cpm_bufs(struct mpc8xxx_spi mspi->rx_dma = mspi->dma_dummy_rx; mspi->map_rx_dma = 0; } + if (t->bits_per_word == 16 && t->tx_buf) { + const u16 *src = t->tx_buf; + u16 *dst; + int i; + + dst = kmalloc(t->len, GFP_KERNEL); + if (!dst) + return -ENOMEM; + + for (i = 0; i < t->len >> 1; i++) + dst[i] = cpu_to_le16p(src + i); + + mspi->tx = dst; + mspi->map_tx_dma = 1; + } if (mspi->map_tx_dma) { void *nonconst_tx = (void *)mspi->tx; /* shut up gcc */ @@ -173,6 +189,13 @@ void fsl_spi_cpm_bufs_complete(struct mp if (mspi->map_rx_dma) dma_unmap_single(dev, mspi->rx_dma, t->len, DMA_FROM_DEVICE); mspi->xfer_in_progress = NULL; + + if (t->bits_per_word == 16 && t->rx_buf) { + int i; + + for (i = 0; i < t->len; i += 2) + le16_to_cpus(t->rx_buf + i); + } } EXPORT_SYMBOL_GPL(fsl_spi_cpm_bufs_complete); --- a/drivers/spi/spi-fsl-spi.c +++ b/drivers/spi/spi-fsl-spi.c @@ -368,6 +368,9 @@ static int fsl_spi_do_one_msg(struct spi return -EINVAL; if (t->bits_per_word == 16 || t->bits_per_word == 32) t->bits_per_word = 8; /* pretend its 8 bits */ + if (t->bits_per_word == 8 && t->len >= 256 && + (mpc8xxx_spi->flags & SPI_CPM1)) + t->bits_per_word = 16; } }