Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754887AbcDJUON (ORCPT ); Sun, 10 Apr 2016 16:14:13 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:53080 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758725AbcDJS6c (ORCPT ); Sun, 10 Apr 2016 14:58:32 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Russell King , Adrian Hunter , Gregory CLEMENT , Ulf Hansson Subject: [PATCH 4.5 195/238] mmc: sdhci: avoid unnecessary mapping/unmapping of align buffer Date: Sun, 10 Apr 2016 11:36:12 -0700 Message-Id: <20160410183507.036402043@linuxfoundation.org> X-Mailer: git-send-email 2.8.0 In-Reply-To: <20160410183456.398741366@linuxfoundation.org> References: <20160410183456.398741366@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4803 Lines: 147 4.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Russell King commit edd63fcc97cdb53279a7c43fa1691f5913d92793 upstream. Unnecessarily mapping and unmapping the align buffer for SD cards is expensive: performance measurements on iMX6 show that this gives a hit of 10% on hdparm buffered disk reads. MMC/SD card IO comes from the mm/vfs which gives us page based IO, so for this case, the align buffer is not going to be used. However, we still map and unmap this buffer. Eliminate this by switching the align buffer to be a DMA coherent buffer, which needs no DMA maintenance to access the buffer. Signed-off-by: Russell King Signed-off-by: Adrian Hunter Tested-by: Gregory CLEMENT Signed-off-by: Ulf Hansson Signed-off-by: Greg Kroah-Hartman --- drivers/mmc/host/sdhci.c | 54 +++++++++++++++-------------------------------- 1 file changed, 18 insertions(+), 36 deletions(-) --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -465,8 +465,6 @@ static void sdhci_adma_mark_end(void *de static int sdhci_adma_table_pre(struct sdhci_host *host, struct mmc_data *data) { - int direction; - void *desc; void *align; dma_addr_t addr; @@ -483,20 +481,9 @@ static int sdhci_adma_table_pre(struct s * We currently guess that it is LE. */ - if (data->flags & MMC_DATA_READ) - direction = DMA_FROM_DEVICE; - else - direction = DMA_TO_DEVICE; - - host->align_addr = dma_map_single(mmc_dev(host->mmc), - host->align_buffer, host->align_buffer_sz, direction); - if (dma_mapping_error(mmc_dev(host->mmc), host->align_addr)) - goto fail; - BUG_ON(host->align_addr & SDHCI_ADMA2_MASK); - host->sg_count = sdhci_pre_dma_transfer(host, data); if (host->sg_count < 0) - goto unmap_align; + return -EINVAL; desc = host->adma_table; align = host->align_buffer; @@ -570,22 +557,7 @@ static int sdhci_adma_table_pre(struct s /* nop, end, valid */ sdhci_adma_write_desc(host, desc, 0, 0, ADMA2_NOP_END_VALID); } - - /* - * Resync align buffer as we might have changed it. - */ - if (data->flags & MMC_DATA_WRITE) { - dma_sync_single_for_device(mmc_dev(host->mmc), - host->align_addr, host->align_buffer_sz, direction); - } - return 0; - -unmap_align: - dma_unmap_single(mmc_dev(host->mmc), host->align_addr, - host->align_buffer_sz, direction); -fail: - return -EINVAL; } static void sdhci_adma_table_post(struct sdhci_host *host, @@ -605,9 +577,6 @@ static void sdhci_adma_table_post(struct else direction = DMA_TO_DEVICE; - dma_unmap_single(mmc_dev(host->mmc), host->align_addr, - host->align_buffer_sz, direction); - /* Do a quick scan of the SG list for any unaligned mappings */ has_unaligned = false; for_each_sg(data->sg, sg, host->sg_count, i) @@ -2984,14 +2953,21 @@ int sdhci_add_host(struct sdhci_host *ho &host->adma_addr, GFP_KERNEL); host->align_buffer_sz = SDHCI_MAX_SEGS * SDHCI_ADMA2_ALIGN; - host->align_buffer = kmalloc(host->align_buffer_sz, GFP_KERNEL); + host->align_buffer = dma_alloc_coherent(mmc_dev(mmc), + host->align_buffer_sz, + &host->align_addr, + GFP_KERNEL); if (!host->adma_table || !host->align_buffer) { if (host->adma_table) dma_free_coherent(mmc_dev(mmc), host->adma_table_sz, host->adma_table, host->adma_addr); - kfree(host->align_buffer); + if (host->align_buffer) + dma_free_coherent(mmc_dev(mmc), + host->align_buffer_sz, + host->align_buffer, + host->align_addr); pr_warn("%s: Unable to allocate ADMA buffers - falling back to standard DMA\n", mmc_hostname(mmc)); host->flags &= ~SDHCI_USE_ADMA; @@ -3003,10 +2979,14 @@ int sdhci_add_host(struct sdhci_host *ho host->flags &= ~SDHCI_USE_ADMA; dma_free_coherent(mmc_dev(mmc), host->adma_table_sz, host->adma_table, host->adma_addr); - kfree(host->align_buffer); + dma_free_coherent(mmc_dev(mmc), host->align_buffer_sz, + host->align_buffer, host->align_addr); host->adma_table = NULL; host->align_buffer = NULL; } + + /* dma_alloc_coherent returns page aligned and sized buffers */ + BUG_ON(host->align_addr & SDHCI_ADMA2_MASK); } /* @@ -3469,7 +3449,9 @@ void sdhci_remove_host(struct sdhci_host if (host->adma_table) dma_free_coherent(mmc_dev(mmc), host->adma_table_sz, host->adma_table, host->adma_addr); - kfree(host->align_buffer); + if (host->align_buffer) + dma_free_coherent(mmc_dev(mmc), host->align_buffer_sz, + host->align_buffer, host->align_addr); host->adma_table = NULL; host->align_buffer = NULL;