From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-lf0-x22c.google.com ([2a00:1450:4010:c07::22c]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1a6Ggl-0005Ae-FI for barebox@lists.infradead.org; Tue, 08 Dec 2015 11:44:12 +0000 Received: by lfaz4 with SMTP id z4so10894082lfa.0 for ; Tue, 08 Dec 2015 03:43:49 -0800 (PST) Date: Tue, 8 Dec 2015 14:46:37 +0300 From: Peter Mamonov Message-ID: <20151208144637.4c30ad2a@berta> In-Reply-To: <20151207102744.GH11966@pengutronix.de> References: <1440714250-28080-1-git-send-email-antonynpavlov@gmail.com> <1440714250-28080-4-git-send-email-antonynpavlov@gmail.com> <20150828063432.GA18700@pengutronix.de> <20150828184614.d0ec3d17f1800be9093f7fa3@gmail.com> <20150904062048.GT18700@pengutronix.de> <20151206175051.e4a017449d741f3989cdc161@gmail.com> <20151207102744.GH11966@pengutronix.de> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [RFC 3/9] MIPS: add virt_to_phys() and phys_to_virt() To: Sascha Hauer Cc: barebox@lists.infradead.org On Mon, 7 Dec 2015 11:27:44 +0100 Sascha Hauer wrote: > On Sun, Dec 06, 2015 at 05:50:51PM +0300, Antony Pavlov wrote: > > On Fri, 4 Sep 2015 08:20:48 +0200 > > Sascha Hauer wrote: > > > > > On Fri, Aug 28, 2015 at 06:46:14PM +0300, Antony Pavlov wrote: > > > > On Fri, 28 Aug 2015 08:34:32 +0200 > > > > Sascha Hauer wrote: > > > > > > > > > On Fri, Aug 28, 2015 at 01:24:04AM +0300, Antony Pavlov wrote: > > > > > > N.B. phys_to_virt() translates phys address > > > > > > to KSEG1 (uncached) address as barebox mips > > > > > > has no cache support. > > > > > > > > > > What would it take to implement cache support for mips? > > > > lack of the cache support is critical problem for current > > > > barebox mips support. I'm planning to add cache support in > > > > several weeks. This task needs much test efforts for different > > > > boards. > > > > > > > > Anyway I can't carry out cache adding work at one. > > > > But adding virt_to_phys and DMA support will help to add cache > > > > support one day anyway. > > > > > > Looking at this again the virt_to_phys/phys_to_virt macros are not > > > necessary. dma_alloc_coherent() already returns both the virtual > > > address and the DMA address. It should be possible to replace > > > DMA_ADDRESS_BROKEN in the ehci driver with a real pointer and use > > > it appropriatly in the driver. > > > > > > > I have tried to get physical address from dma_alloc_coherent(), > > here is a small part of my patch (just for demonstration): > > > > --- a/drivers/usb/host/ehci-hcd.c > > +++ b/drivers/usb/host/ehci-hcd.c > > @@ -41,6 +41,7 @@ struct ehci_priv { > > struct ehci_hcor *hcor; > > struct usb_host host; > > struct QH *qh_list; > > + dma_addr_t qh_list_dma; > > struct qTD *td; > > int portreset; > > unsigned long flags; > > @@ -403,7 +410,7 @@ ehci_submit_async(struct usb_device *dev, > > unsigned long pipe, void *buffer, goto fail; > > } > > > > - ehci->qh_list->qh_link = > > cpu_to_hc32((uint32_t)ehci->qh_list | QH_LINK_TYPE_QH); > > + ehci->qh_list->qh_link = cpu_to_hc32(ehci->qh_list_dma | > > QH_LINK_TYPE_QH); > > token = hc32_to_cpu(qh->qt_token); > > if (!(token & 0x80)) { > > @@ -1306,7 +1313,7 @@ int ehci_register(struct device_d *dev, > > struct ehci_data *data) ehci->post_init = data->post_init; > > > > ehci->qh_list = dma_alloc_coherent(sizeof(struct QH) * > > NUM_TD, > > - DMA_ADDRESS_BROKEN); > > + &ehci->qh_list_dma); > > ehci->periodic_queue = dma_alloc_coherent(sizeof(struct > > QH), DMA_ADDRESS_BROKEN); > > ehci->td = dma_alloc_coherent(sizeof(struct qTD) * NUM_TD, > > > > > > However ehci_td_buffer() gets buf pointer outside of ehci driver > > (e.g. via usb_bulk_msg()), so it is difficult to avoid > > virt_to_phys() in ehci_td_buffer(), e.g.: > > > > @@ -195,7 +197,7 @@ static int ehci_td_buffer(struct qTD *td, void > > *buf, size_t sz) > > idx = 0; > > while (idx < 5) { > > - td->qt_buffer[idx] = cpu_to_hc32(addr); > > + td->qt_buffer[idx] = > > cpu_to_hc32(virt_to_phys(addr)); next = (addr + 4096) & ~4095; > > delta = next - addr; > > if (delta >= sz) > > > > Have you any idea? > > No. Translating this addres into a physical address seems unavoidable > here. The other solution is to allocate private buffer using dma_alloc_coherent(), use the returned dma address to fill the qt_buffer field, copy data from the supplied buffer to the private buffer before the transaction and copy back after the transaction is done. > I would still prefer a real cache implementation for MIPS > though. Have you looked further into that? The current MIPS > cached/uncached memory windows seem to be a constant source of > problems we could avoid. > > Sascha > > _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox